Expression vector systems and method of use

ABSTRACT

This invention relates to gene therapy by using vectors which encode stable MRNA and methods of using such vectors. In particular, this invention relates to vectors which establish controlled expression of recombinant genes within tissues at certain levels. The vector includes a 5&#39; flanking region which includes necessary sequences for expression of a nucleic acid cassette, a 3&#39; flanking region including a 3&#39; UTR and/or 3&#39; NCR which stabilizes mRNA expressed from the nucleic acid cassette, and a linker which connects the 5&#39; flanking region to a nucleic acid sequence. The linker has a position for inserting a nucleic acid cassette. The linker does not contain the coding sequence of a gene that the linker is naturally associated with. The 3&#39; flanking region is 3&#39; to the position for inserting the nucleic acid cassette. The expression vectors of the present invention can also be regulated by a regulatory system and/or constructed with a coating.

The invention was partially supported by a grant from the United StatesGovernment under HL-38401 awarded by the National Institute of Health.The U.S. Government may have rights in the invention.

RELATED APPLICATION

This application is a continuation-in-part of Schwartz et al., U.S.patent application Ser. No. 07/789,919, filed Nov. 6, 1991, now U.S.Pat. No. 5,298,422, entitled "Myogenic Vector Systems", the whole ofwhich (including drawings) is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates to vectors which encode stable messenger RNA(mRNA) and methods of using such vectors. In particular, this inventionrelates to vectors which establish controlled expression of recombinantgenes within a tissue at levels which are useful for gene therapy andother applications.

The regulation of gene expression can be related to the rate ofmetabolic breakdown of mRNA molecules. Chen et al., J. Bact., vol. 172,No. 8, pp. 4578-4586 (1990). Such decay rates of individual mRNA specieseffects steady state expression levels of the corresponding protein inthe cytoplasm. Id. Thus, the rate at which a particular protein is madeis directly proportional to the cytoplasmic level of the mRNA whichencodes it.

Studies have measured the stabilities of different mRNAs. Regulatorypolypeptide mRNAs such as transcription factors or cytokines are oftenhighly unstable whereas mRNAs for housekeeping proteins or maternalmRNAs which must be stored until after oocyte fertilization tend to bestable. Braverman, G., Cell Vol. 88, pp. 5-6 (1987) ; Rosenthal, E. T.,et al., J.M.B. Vol. 166, pp. 307-327 (1983). Studies have also shownskeletal muscle mRNA to be distributed into two populations with regardto stability. Medford et al., J. Biol. Chem., vol. 258, pp. 11063-11073(1983). One mRNA population has a half life of less than four hours andthe other population has a half life of seventeen to over fifty-fourhours. Id.

Researchers have examined factors which enhance or degrade mRNAstability. For example, the presence of 5' 7-methylguanosinetriphosphate cap structures as well as the 3' poly (A) tails have beenanalyzed as mRNA stabilizers against degradation. Berstein, P., et al.,Trends Biochem. Sci. Vol. 14, pp. 373-377 (1989); Drummond, D. R. etal., Nucleic Acid Res. Vol. 13 pp. 7375-7394 (1985); Sachs, A., Curr.Op. Cell Biol., Vol. 2, pp. 1092-1098 (1990). Studies suggest that thepoly (A) tail and the poly (A) -binding protein (pABP) interact in orderto regulate mRNA stability. Berstein, P., et al., Mol. Cell. Biol. Vol.91 pp. 659-670 (1989). Such studies show increased mRNA stability whenpoly (A) tails are present. Deadenylation of the poly (A) tail, however,does not necessarily result in destabilization. Berstein, P., et al.,Trends Biochem. Sci., Vol. 14, pp. 373-377 (1989).

Elements specific to mRNAs have been identified which can eitherstabilize or destabilize the transcript. These mRNA elements are thoughtto interact with cytoplasmic transacting factors. Studies show thetransferrin receptor mRNA appears to be stabilized when aniron-responsive element in the 3' untranslated region (3'UTR) of themRNA is bound by a specific 90 kDa binding protein. Mullner, E. W., etal., Cell Vol. 58, pp. 373-382 (1989); Casey, J., et al., EMBO J, Vol.8, pp. 3693-3699 (1989). Other stability determining cis-actingsequences are located in the 5' untranslated region (5' UTR) or thecoding region of an mRNA. Jones, T. R., et al., Mol. Cell. Biol. Vol. 7,pp. 4513-4521 (1987); Shyu, A., et al., Genes Dev., Vol. 3, pp. 60-72(1989); Wisdom, R., et al., P.N.A.S., Vol. 86, pp. 3574-3578 (1989).

Studies have also shown that 3' UTRs containing AU-rich sequencescorrelate with rapid mRNA degradation by causing destabilization of theRNA transcript. Caput, et al., P.N.A.S., vol. 83, pp. 1670-1674 (1986);Cleveland, et al., New. Biol., vol. 1, pp. 121-126 (1989). Transcriptsfrom many transiently expressed eukaryotic genes, including lymphokinegenes and protooncogenes (c-myc and c-fos) contain AU-rich sequences intheir 3' UTRs and are rapidly degraded in the cytoplasm. Schuler, etal., Cell, vol. 55, pp. 1115-1122 (1988) ; Shaw, et al., Genes & Dev.,vol. 3, pp. 60-72 (1989). These studies have shown that deletion ofAU-rich sequences from the c-fos or c-myc 3'UTR confers stability upontranscripts produced from transfected constructs. Wilson, et al.,Nature, vol. 336, pp. 396-399 (1988); Jones, et al., Mol. Cell. Biol.,vol. 7, pp. 4513-4521 (1987).

In addition, studies have shown that introduction of a AU-rich sequencefrom the granulocyte-macrophage colony-stimulating factor (GM-CSF) 3'UTRinto the 3'UTR of the rabbit β-globin gene confers instability upon theotherwise stable β-globin mRNA. Shaw, et al., Cell, vol. 46, pp. 659667(1986). AU-rich sequences have also been detected in the 3'UTR ofinterleukin-2, tumor necrosis factor-α and Human B Cell StimulatoryFactor II. Bohjanen, Mol. Cell. Biol., vol. 11, no. 6, pp. 3228-3295(1991); Tonouchi, et al., Bio. Biopph. Res. Com., vol. 163, no. 2, pp.1056-1062 (1989).

Studies have also compared the sequence of UTRs in vertebrateskeletal-α, cardiac-α and β-actin mRNA. These studies revealed regionsof high sequence homology within the 3'UTR portion of each of theseactin isoformic mRNA. This homology is greater among the a-cardiac andskeletal actin isoforms than between the α-skeletal actin and β-actinisoform mRNAs. Mayer, et al., Nucl. Acids Res., vol. 12, pp. 1087-1100(1984); Ponte et al., Nucl. Acids Res., vol. 12, pp. 1687-1696 (1984);Chang et al., Nucl. Acids Res., vol. 13, pp. 1223-1237 (1985). Incomparison, 3'UTR sequences of other vertebrate genes, such as thoseencoding insulin and prolactin, share common coding regions but usuallycontain divergent 3'UTRs. Mayer et al., supra, Ponte et al., supra.

SUMMARY OF THE INVENTION

The applicant has identified RNA stability elements located in the 3'UTRs and/or 3' non-coding regions (3' NCR) of eukaryotic genes.Applicant has determined that it is useful to construct vectors basedupon these particular 3' UTRs and/or 3' NCRs. Specifically, theseregions increase the expression of nucleic acid sequences containedwithin vectors by stabilizing the RNA transcripts and enhancing thetranscriptional and translational processes.

In addition, expression of these vectors can be tissue specific. Thesevectors are useful in facilitating enhanced expression in tissues aswell as useful in targeting expression with tissue specificity. Thesevectors can be used to treat diseases by gene therapy by targeting thevectors to tissues where the vector is expressed. Vectors containingsuch sequences are able to provide controlled expression of recombinantgenes within tissues at certain levels that are useful for gene therapyand other applications. These vectors can also be used to createtransgenic animals for research or livestock improvement.

Stability of mRNA relates to the rate of metabolic breakdown or decay ofan mRNA molecule within a cell. The stability correlates directly withthe rate of expression of a given gene, i.e., synthesis of thecorresponding protein. Decay rates of MRNA affects the steady stateexpression levels of a gene. We have determined that 3'UTR sequences asdefined below provide mRNA stability. By using 3'UTR sequences with thevectors of the present invention, the decay rates of mRNAs encoded bythe vectors are reduced, i.e., increased mRNA stability. The increasedstability causes increased expression.

Taking advantage of the unique mRNA stability provided during expressionof the vectors as well as the tissue specificity, the present inventionfeatures use of a vector to enhance expression of any specific nucleicacid sequence in tissue. In particular, the present inventiondemonstrates that by utilizing certain 3'UTR and 3'NCR sequences,expression is enhanced due to specific stability of mRNA. Such stabilityhelps in the transcription and translation processes of mmRNA. Theincreased mRNA stability in cells caused by the 3'UTR and 3'NCR providesa higher level of mRNA accumulation. This increased mRNA stability leadsto increased levels of protein production. In addition, the expressionvectors may be constructed to provide expression of exogenous DNA withtissue specificity. Furthermore, the expression vectors can beconstructed so as to regulate, through other factors, the expression ofthe exogenous DNA.

This unique ability of the expression vector to provide enhanced mRNAstability as well as direct expression to specific tissues allows thevector to be used for treating numerous diseases. The above vectors canbe used in gene therapy where a vector encoding a therapeutic product isintroduced into a tissue so that tissue will express the therapeuticproduct. For example, the above vectors may be used for treating muscleatrophy associated with neurological, muscular, or systemic disease oraging by causing tissues to express certain trophic factors. The abovevectors may be used for treating hemophilias by causing tissues toexpress certain clotting factors and secrete these factors into thecirculation. Furthermore, the vectors above can be used for preventingor treating atherogenesis and atherosclerotic cardiovascular,cerebrovascular, or peripheral-vascular disease by causing tissue toexpress certain factors involved in lipid metabolism.

In addition, the vectors above can be used for gene replacement ofinherited genetic defects or acquired hormone deficiencies such asdiabetes, for vaccination in humans or animals to induce immuneresponses, or for creating transgenic animals. The transgenic animalscan be used as models for studying human diseases, for assessing andexploring novel therapeutic methods, to assess the effects of chemicaland physical carcinogens, and to study the effect of various genes andgenetic regulatory elements. Furthermore, transgenic animals can be usedto develop commercially important livestock species. The above vectorscan also be used to transform cells to produce particular proteins andRNA in vitro.

In a first aspect, the present invention features a vector forexpression of a nucleic acid sequence in tissue by encoding stable mRNA.The vector includes a 5' flanking region which includes necessarysequences for the expression of a nucleic acid cassette, a 3' flankingregion encoding a region, including a 3'UTR and/or a 3' NCR, whichstabilizes mRNA expressed from the nucleic acid cassette, and a linkerwhich connects the 5' flanking region to a nucleic acid. The linker doesnot contain the coding sequence of a gene that the linker is naturallyassociated with. That is, the linker is not the normal gene associatedwith the 5' and 3' regions. The 3' flanking region is 3' to the positionfor inserting the nucleic acid cassette.

Stability of mRNA as discussed above and as used herein refers to therate of metabolic breakdown or decay of an mRNA molecule within a cell.The faster the turnover, i.e., breakdown, of mRNA the less stable themRNA is within a cell. In contrast, the slower the turnover of a mRNAthe more stable the mRNA is within a cell. Such stability correlatesdirectly with the rate of expression of a given gene, i.e., synthesis ofthe corresponding protein. These decay rates of individual mRNA speciesdirectly effects the steady state expression levels of a gene in thecytoplasm, i.e., increased stability causes increase in expression.

The 3' flanking region containing sequences for regions such as the3'UTR and/or 3'NCR, as defined below, provide mRNA stability in a numberof ways. These include but are not limited to providing a particularmRNA structure which protects the mRNA from degradation within thecytoplasm. This includes mRNA secondary structures as well as sequencesand/or factors which recognize an appropriate trans acting regulatoryfactors or respond to regulatory system, i.e., mRNA stability regulatedby hormones and other physiological effectors. This does not includemRNA stability due to a poly (A) sequence. Poly (A) sequences are notencoded by the DNA themselves but are added to the mRNA oncetranscription has occurred due to signals from the sequences transcribedinto the mRNA.

The stability of mRNA can be determined by various methods such asmeasuring mRNA half-life. The half life is the elapsed time during whichhalf of the mRNA in a cell is eliminated. The mRNA half life is longerif the nucleic acid cassette encodes a 3'UTR and/or 3'NCR sequence thanwhen it does not. Half-life measurements can be performed by pulse chasemethods using ³ H! uridine as described below, or by other methods knownin the art. In addition to half life, other methods known in the art canalso be used to measure mRNA stability. Hentze, M. W., Biochimica etBiophysica Acta, Vol. 1090, pp. 281-292 (1991).

The term "flanking region" as used herein refers to nucleotide sequenceson either side of an associated gene. Flanking regions can be either 3'or 5' to a particular gene in question. In general, flanking sequencescontain elements necessary for regulation of expression of a particulargene. Such elements include, but are not limited to, sequences necessaryfor efficient expression, as well as tissue specific expression.Examples of sequences necessary for efficient expression can includespecific regulatory sequences or elements adjacent to or within theprotein coding regions of DNA. These elements, located adjacent to thegene, are termed cis-acting elements. The signals are recognized byother diffusible biomolecules in trans to alter the transcriptionalactivity. These biomolecules are termed trans-acting factors.Trans-acting factors and cis-acting elements have been shown tocontribute to the timing and developmental expression pattern of a gene.Cis-acting elements are usually thought of as those that regulatetranscription and are usually found within promoter regions and withinupstream (5') or downstream (3') DNA flanking regions.

Flanking DNA with regulatory elements that regulate expression of genesin tissue may also include modulatory or regulatory sequences which areregulated by specific factors, such as glucocorticoids, androgens,vitamin D₃ and its metabolites, vitamin A and its metabolites, retinoicacid, calcium as well as others. "Modulatory" or "regulatory" sequencesas used herein refer to sequences which may be in the 3' or 5' flankingregion, where such sequences can enhance activation and/or suppressionof the transcription of the associated gene. "Responsive" or "respond"as used herein refers to the enhancement of activation and/orsuppression of gene transcription as discussed below. "Metabolite" asused herein refers to any product from the metabolism of the regulatoryfactors which regulate gene expression.

In addition to the above, the flanking regions, whether 3' or 5', cancause tissue specificity. Such tissue specificity provides expressionpredominantly in a specified cell or tissue. "Predominantly" as usedherein means that the gene associated with the 3' or 5' flanking regionis expressed to a higher degree only in the specific tissue as comparedto low expression or lack of expression in nonspecific tissue. The 3' or5' flanking regions singularly or together as used herein can provideexpression of the associated gene in other tissues but to a lower degreethan expression in tissues or cells where expression is predominate.Expression is preferentially in the specified tissue. Such predominantexpression can be compared with the same magnitude of difference as willbe found in the natural expression of the gene (i.e. as found in a cellin vivo) in that particular tissue or cell type as compared with othernonspecific tissues or cells. Such differences can be observed byanalysis of mRNA levels or expression of natural gene products,recombinant gene products, or reporter genes. Furthermore, northernanalysis, X gal immunofluorescence or CAT assays as discussed herein andas known in the art can be used to detect such differences.

The 3' flanking region contains sequences or regions, e.g. 3'UTR and/or3' NCR, which regulate expression of a nucleic acid sequence with whichit is associated. The 3' flanking regions can provide tissue-specificexpression to an associated gene. The 3' flanking region also contains atranscriptional termination signal. The term 3' flanking region as usedherein includes that portion of a naturally occurring sequence 3' to thetranscribed portion of the gene which are responsible for mRNAprocessing and/or tissue-specific expression. That portion can bereadily defined by known procedures. For example, the portions of a 3'flanking region which are responsible for mRNA stability and/ortissue-specific expression can be mapped by mutational analysis orvarious clones created to define the desired 3' flanking region activityin a selected vector system.

The 3' flanking region can contain a 3'UTR and/or a 3' NCR. The term "3'untranslated region" or "3'UTR" refers to the sequence at the 3' end ofstructural gene which is transcribed from the DNA but not translatedinto protein. In addition, the actual nucleotides that promote the 3'stabilizing effects may extend within the coding region of the gene.This 3'UTR region does not contain a poly(A) sequence. Poly (A)sequences are only added after the transcriptional process.

Myogenic-specific 3'UTR sequences can be used to allow for specificstability in muscle cells or other tissues. As described below,myogenic-specific sequences refers to gene sequences normally expressedin muscle cells, e.g., skeletal, heart and smooth muscle cells. Myogenicspecific mRNA stability provides an increase in mRNA stability withinmyogenic cells. The increase in stability provides increased expression.The 3'UTR and 3' NCR sequences singularly or together can provide ahigher level of mRNA accumulation through increased mRNA stability.Thus, increased expression and/or stability of mRNA leads to increasedlevels of protein production.

The term "3' non-coding region" or "3'NCR" is a region which is adjacentto the 3'UTR region of a structural gene. The 3'NCR region generallycontains a transcription termination signal. Once transcription occursand prior to translation, the RNA sequence encoded by the 3'NCR isusually removed so that the poly (A) sequence can be added to the mRNA.The 3'NCR sequences can also be used to allow mRNA stability asdescribed above. The 3'NCR may also increase the transcription rate ofthe nucleic acid cassette.

The 3'UTR and 3' NCR sequences can be selected from a group ofmyogenic-specific genes. Examples of myogenic-specific genes include theskeletal u-actin gene, fast myosin-light chain 1/3 gene, myosin-heavychain gene, troponin T gene, acetylcholine receptor subunit genes andmuscle creatinine kinase gene.

The 5' flanking region is located 5' to the associated gene or nucleicacid sequence to be expressed. Just as with the 3' flanking region, the5' flanking region can be defined by known procedures. For example, theactive portion of the 5' flanking region can be mapped by mutationalanalysis or various clones of the 5' flanking region created to definethe desired activity in a selected vector. The 5' flanking region caninclude, in addition to the above regulatory sequences or elements, apromoter, a TATA box, and a CAP site, which are in an appropriaterelationship sequentially and positionally for the expression of anassociated gene. In this invention, "necessary sequences" are thoseelements of the 5' flanking region which are sequentially andpositionally in an appropriate relationship to cause controlledexpression of a gene within a nucleic acid cassette. Expression iscontrolled to certain levels within tissues such that the expressed geneis useful for gene therapy and other applications. The 5' sequence cancontain elements which regulate tissue-specific expression or caninclude portions of a naturally occurring 5' element responsible fortissue-specific expression.

The term "promoter," as used herein refers to a recognition site on astrand of DNA to which RNA polymerase binds. The promoter usually is aDNA fragment of about 100 to about 200 base pairs (in eukaryotic genes)in the 5' flanking DNA upstream of the CAP site or the transcriptionalinitiation start site. The promoter forms an "initiation complex" withRNA polymerase to initiate and drive transcriptional activity. Thecomplex can be modified by activating sequences termed "enhancers" orinhibitory sequences termed "silencers". The promoter can be one whichis naturally (i.e. , associated as if it were within a cell in vivo) ornon-naturally associated with a SI flanking region.

A variety of promoters can be used in the vectors of the presentinvention. Some examples include thymidine kinase promoter,myogenic-specific promoters including skeletal α-actin gene promoter,fast myosin light chain 1 promoter, myosin heavy chain promoter,troponin T promoter, and muscle creatinine kinase promoter, as well asnon-specific promoters including the cytomegalovirus immediate earlypromoter, Rous Sarcoma virus LTR. These promoters or other promotersused with the present invention can be mutated in order to increaseexpression of the associated gene. Mutation as used herein refers to achange in the sequence of genetic material from normal causing a changein the functional characteristics of the gene. This includes genemutations where only a single base is changed in the natural genepromoter sequences or multiple bases are changed. Furthermore a promotermay be used by itself or in combination with elements from otherpromoters, as well as various enhancers, transcript stabilizers, orother sequences capable of enhancing function of the vector.

The term "intron" as used herein refers to a section of DNA occurring ina transcribed portion of a gene which is included in a precursor RNA butis then excised during processing of the transcribed RNA beforetranslation occurs. Intron sequences are therefore not found in mRNA nortranslated into protein. The term "exon" as used herein refers to aportion of a gene that is included in a transcript of a gene andsurvives processing of the RNA in the cell to become part of a mRNA.Exons generally encode three distinct functional regions of the RNAtranscript. The first, located at the 5' end which is not translatedinto protein, termed the 5' untranslated region (5' UTR) , signals thebeginning of RNA 5 transcription and contains sequences that direct themRNA to the ribosomes and cause the mRNA to be bound by ribosomes sothat protein synthesis can occur. The second contain the informationthat can be translated into the amino acid sequence of the protein orfunction as a bioactive RNA molecule. The third, located at the 3' endis not translated into protein, i.e. 3' UTR, contains the signals fortermination of translation and for the addition of a polyadenylationtail (poly(A). In particular, the 3' UTR as defined above can provideMRNA stability. The intron/exon boundary will be that portion in aparticular gene where an intron section connects to an exon section. Theterms "TATA box" and "CAP site" are used as they are recognized in theart.

The term "linker" as used herein refers to DNA which contains therecognition site for a specific restriction endonuclease. Linkers may beligated to the ends of DNA fragments prepared by cleavage with someother enzyme. In particular, the linker provides a recognition site forinserting the nucleic acid cassette which contains a specific nucleicsequence to be expressed. This recognition site may be but is notlimited to an endonuclease site in the linker, such as Cla-I, Not-I,Xmal, Bgl-II, Pac-I, Xhol, Nhel, Sfi-I. A linker can be designed so thatthe unique restriction endonuclease site contains a start codon (e.g.AUG) or stop codon (e.g. TAA, TGA, TCA) and these critical codons arereconstituted when a sequence encoding a protein is ligated into thelinker. Such linkers commonly include an NcoI or SphI site.

The term "leader" as used herein refers to a DNA sequence at the 5' endof a structural gene which is transcribed and translated along with thegene. The leader usually results in the protein having an n-terminalpeptide extension sometimes called a pro-sequence. For proteins destinedfor either secretion to the extracellular medium or the membrane, thissignal sequence directs the protein into endoplasmic reticulum fromwhich it is discharged to the appropriate destination. The leadersequence normally is encoded by the desired nucleic acid, syntheticallyderived or isolated from a different gene sequence. A variety of leadersequences from different proteins can be used in the vectors of thepresent invention. Some non-limiting examples include gelsolin, albumin,fibrinogen and other secreted serum proteins.

The term "vector" as used herein refers to a nucleic acid, e.g., DNAderived from a plasmid, cosmid, phasmid or bacteriophage or synthesizedby chemical or enzymatic means, into which one or more fragments ofnucleic acid may be inserted or cloned which encode for particulargenes. The vector can contain one or more unique restriction sites forthis purpose, and may be capable of autonomous replication in a definedhost or organism such that the cloned sequence is reproduced. The vectormay have a linear, circular, or supercoiled configuration and may becomplexed with other vectors or other materials for certain purposes.The components of a vector can contain but is not limited to a DNAmolecule incorporating: (1) DNA; (2) a sequence encoding a therapeuticor desired product; and (3) regulatory elements for transcription,translation, RNA stability and replication. A viral vector in this senseis one that contains a portion of a viral genome, e.g., a packagingsignal, and is commonly useful not merely as DNA but as a gene locatedwithin a viral particle.

The purpose of the vector is to provide expression of a nucleic acidsequence in tissue. In the present invention this expression is enhancedby providing stability to an mRNA transcript from the nucleic acidsequence. Expression includes the efficient transcription of an insertedgene or nucleic acid sequence within the vector. Expression products maybe proteins including but not limited to pure protein (polypeptide),glycoprotein, lipoprotein, phosphoprotein, or nucleoprotein. Expressionproducts may also be RNA. The nucleic acid sequence is contained in anucleic acid cassette. Expression of the nucleic acid can be continuousor controlled by endogenous or exogenous stimuli.

The term "control" or "controlled" as used herein relates to theexpression of gene products (protein or RNA) at sufficiently high levelssuch that a therapeutic effect is obtained. Levels that are sufficientfor therapeutic effect are lower than the toxic levels. Levels ofexpression for therapeutic effect within selected tissues corresponds toreproducible kinetics of uptake, elimination from cell,post-translational processing, and levels of gene expression, and, incertain instances, regulated expression in response to certainendogenous or exogenous stimuli (e.g., hormones, drugs).

The term "nucleic acid cassette" as used herein refers to the geneticmaterial of interest which codes for a protein or RNA. The nucleic acidcassette is positionally and. sequentially oriented within the vectorsuch that the nucleic acid in the cassette can be transcribed into RNA,and when necessary, translated into a protein in the transformed tissueor cell. Preferably, the cassette has 3' and SI ends adapted for readyinsertion into a vector, e.g., it has restriction endonuclease sites ateach end.

A variety of proteins can be encoded by the sequence in a nucleic acidcassette in the transformed tissue or cell. Those proteins which can beexpressed may be located in the cytoplasm, nucleus, membranes (includingthe plasmalemma, nuclear membrane, endoplasmic reticulum or otherinternal membrane compartments), in organelles (including themitochondria, peroxisome, lysosome, endosome or other organelles), orsecreted. Those proteins may function as intracellular or extracellularstructural elements, ligand, hormones, neurotransmitter, growthregulating factors, differentiation factors, gene-expression regulatingfactors, DNA-associated proteins, enzymes, serum proteins, receptors,carriers for small molecular weight organic or inorganic compounds,drugs, immunomodulators, oncogenes, tumor suppressor, toxins, tumorantigens, or antigens. These proteins may have a natural sequence or amutated sequence to enhance, inhibit, regulate, or eliminate theirbiological activity.

Specific examples of these compounds include proinsulin, insulin, growthhormone, growth hormone release factor, androgen receptors, insulin-likegrowth factor I, insulin-like growth factor II, insulin-like growthfactor binding protein, erythropoietin, clotting factors (VII, VIII, IX,others), chorionic gonadotropin, prolactin, endorphin, enkephalins,epidermal growth factor, TGF-α, TGF-β, nerve growth factors, dermalgrowth factor (PDGF), angiogenesis factors (e.g., acidic fibroblastgrowth factor, basic fibroblast growth factor and angiogenin) ,antiangiogenesis factors (interferon-α, interferon-β, interferon-γ,thrombospondin), brain growth factors, ciliary growth factors, matrixproteins (e.g., type IV collagen, type VII collagen, laminin), oncogenes(e.g., ras, fos, myc, erb, src, sis, jun), E6 or E7 transformingsequence, p53 protein, dystrophin, cytokinereceptors, interleukins(IL-1, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12), interleukin inhibitors,viral capsid protein, viral reverse transcriptase, HIV-encoded protein,and antigens from eukaryotic, viral, bacterial, fungal, yeast, andparasitic organisms which can be used to induce an immunologic response.

In addition, the nucleic acid cassette can code for RNA. The RNA mayfunction as a template for translation, as an antisense inhibitor ofgene expression, as a triple-strand forming inhibitor of geneexpression, as an enzyme (ribozyme) or as a ligand recognizing specificstructural determinants on cellular structures for the purpose ofmodifying their activity. Specific examples include RNA molecules toinhibit the expression or function of prostaglandin synthase,lipo-oxenganse, histocompatibilty antigens (class I or class II) celladhesion molecules, nitrous oxide synthase, β₂ microglobulin, oncogenes,and growth factors. These are only examples and are not meant to belimiting in any way.

The compounds which can be incorporated are only limited by theavailability of the nucleic acid sequence for the protein or RNA to beincorporated. One skilled in the art will readily recognize that as moreproteins or RNAs become identified they can be integrated into thevector system of the present invention and expressed in animal or humantissue.

The term "tissue" as used herein refers to a collection of cellsspecialized to perform a particular function or can include a singlecell. The cells may be of the same type or of different types.

The term "gene", e.g., "myogenic genes," as used herein refers to thosegenes exemplified herein and their equivalence in other animal speciesor other tissues. Homologous sequences (i.e. sequences having a commonevolutionary origin representing members of the same superfamily) oranalogous sequences (i.e. sequences having common properties though adistinct evolutionary origin) are also included so long as they provideequivalent properties to those described herein. It is important in thisinvention that the chosen sequence provide the MRNA stability, enhancedlevels of expression, expression of the appropriate product, and/ortissue-specific expression as noted herein. Those in the art willrecognize that the minimum sequences required for such functions areencompassed by the above definition. These minimum sequences are readilydetermined by standard techniques exemplified herein.

The term "`myogenic" refers to muscle tissue or cells. The muscle tissueor cells can be in vivo, in vitro, or in vitro tissue culture andcapable of differentiating into muscle tissue. Myogenic cells includeskeletal, heart and smooth muscle cells. Genes are termed "myogenic" or"myogenic-specific" if they are expressed or expressed preferentially inmyogenic cells. Vectors are termed "myogenic" or "myogenic-specific" ifthey function preferentially in myogenic muscle tissue or cells.Myogenic activity of vectors can be determined by transfection of thesevectors into myogenic cells in culture, injected into intact muscletissue, or injected into mammalian oocytes to be stably incorporatedinto the genome to generate transgenic animals which express the proteinor RNA of interest in myogenic cells.

The term "non-myogenic" refers to tissue or cells other than muscle. Thetissues or cells can be in vivo, in vitro, or in vitro tissue culture.

In a preferred embodiment, the vector described above may have its 5'flanking region and/or its 3' flanking region from myogenic genes, inparticular the skeletal α-actin gene. The 3'UTR of the chicken skeletalα-actin gene starts at nucleotide 2060 and extends to 2331 (SequenceI.D. No. 1), approximately 0.3 Kb. The complete 3' flanking region witha 3'UTR and contiguous 3' NCR of the gene extends an additional 2.0 Kb.This 2.3 Kb fragment can be linked immediately following the naturaltranslation termination codon to a cDNA sequence coding for the proteinor RNA to be expressed. As discussed above, these regions can be furtherand more precisely defined by routine methodology, e.g. deletion ormutation analysis or their equivalents. Preferably, the vector containssuch a 3' region or 5' region comprising, consisting, or consistingessentially of the regions disclosed above. The terms "comprising,""consisting," or "consisting essentially of" as used herein (withrespect to a vector with the 3' or 5' regions of the present invention)includes those regions as well as those regions above in which thesequence is changed but the desired vector activity remains equivalent.Such a change, for example, could be a change of ten nucleotides in anyof the above regions. This is only an example and is non-limiting.

In addition, another embodiment of the above vector may contain aregulatory system for regulating expression of the nucleic acidcassette. The term "regulatory system" as used herein refers tocis-acting or trans-acting sequences incorporated into the above vectorswhich regulate in some characteristic the expression of the nucleic acidof interest as well as trans-acting gene products which are co-expressedin the cell with the above described vector. Regulatory systems can beused for up-regulation or down regulation of expression from the normallevels of expression or existing levels of expression at the time ofregulation. The system contributes to the timing and developmentalexpression pattern of the nucleic acid.

One construction of a regulatory system includes a chimeric trans-actingregulatory factor incorporating elements of a serum response factorcapable of regulating expression of the vector in a cell. The chimerictransacting regulatory factor is constructed by replacing the normal DNAbinding domain sequence of the serum response factor with a DNA bindingdomain sequence of a receptor. The serum response factor has atransactivation domain which is unchanged. The transactivation domain iscapable of activating transcription when an agent or ligand specific tothe receptor binding site binds to the receptor. Thus, regulation can becontrolled by controlling the amount of the agent.

The DNA binding domain sequence of a receptor, incorporated into thechimeric trans-activating regulatory factor, can be selected from avariety of receptor groups including but not limited to vitamin,steroid, thyroid, orphan, hormone, retinoic acid, thyroxine, or GAL4receptors. The chimeric trans-activating regulator factor is usuallylocated within the sequence of the promoter. In one preferred embodimentthe promoter used in the vector is the -actin promoter and the receptoris the vitamin D receptor.

Another embodiment of the regulatory system includes the construction ofa vector with two functional units. One functional unit expresses areceptor. This functional unit contains elements required for expressionincluding a promoter, a nucleic acid sequence coding for the receptor,an d a 3' UTR and/or a 3' NCR. The second functional unit expresses atherapeutic protein or RNA and contains, in addition, a response elementcorresponding to the receptor, a promoter, a nucleic acid cassette, anda 3' UTR and/or a 3' NCR. These functional units can be in the same orseparate vectors.

The first functional unit expresses the receptor. It is favorable to usea receptor not found in high levels in the target tissue. The receptorforms an interaction, e.g., ionic, nonionic, hydrophobic, with theresponse element on the second functional unit prior to, concurrentwith, or after the binding of the agent or ligand to the receptor. Thisinteraction allows the regulation of the nucleic acid cassetteexpression. The receptor can be from the same nonlimiting group asdisclosed above. Furthermore, the vector can be myogenic specific byusing myogenic specific 3' UTR and/or 3' NCR sequences.

A second related aspect of the invention features a transgenic animalwhose cells contain the vectors of the present invention. These cellsinclude germ or somatic cells. The transgenic animals can be used asmodels for studying human diseases, for assessing and exploring noveltherapeutic methods, to assess the effects of chemical and physicalcarcinogens, and to study the effect of various genes and geneticregulatory elements. In addition, transgenic animals can be used todevelop commercially important livestock species.

A third related aspect of the present invention features cellstransformed with a vector of the present invention for expression of anucleic acid sequence. As described above, the nucleic acid cassette maycontain genetic material and code for a variety of proteins or RNA.

As used herein, "transformation" is the change in a cell's phenotypiccharacteristics by the action of a gene expressing a gene product. Thegene causing the phenotypic characteristic change has been transfectedinto the cell. The term "transfection" as used herein refers to amechanism of gene transfer which involves the uptake of DNA by a cell ororganism. Following entry into the cell, the transforming DNA mayrecombine with that of the host by physically integrating into thechromosomes of the host cell, may be maintained transiently as anepisomal element without being replicated, or may replicateindependently as a plasmid. Transfection can be performed by in vivotechniques as described below, or by ex vivo techniques in which cellsare co-transfected with a vector containing a selectable marker. Thisselectable marker is used to select those cells which have becometransformed. It is well known to those skilled in the art the type ofselectable markers to be used with transfection/transformation studies.Transfection/transformation can be tissue-specific, i.e., involve theuse of myogenic specific vectors which cause expression of the nucleicacid cassette predominantly in the tissue of choice. In particular,tissue specificity can be directed to myogenic cells by using 3'UTRand/or 3' NCR sequences specific for myogenic tissue expression.

The transformed cell can produce a variety of compounds selected fromproteins or RNA described above in the discussion of nucleic acidcassettes. The product expressed by the transformed cell depends on thenucleic acid in the translated region of the nucleic acid cassettewithin the vector.

A fourth related aspect of the present invention features methods fortransfecting a cell with the vectors of the present invention. Thesemethods comprise the steps of contacting a cell in situ with a vector ofthe present invention for sufficient time to transfect the cell. Asdiscussed above, transfection can be in vivo or ex vivo.

A fifth related aspect of the present invention features a method fortreating disease by transfecting cells with the above-referencedvectors. Disease can include but is not limited to muscle atrophy,atherogenesis, atherosclerotic cardiovascular, cerebrovascular, orperipheral vascular disease, diabetes, neuropathy, growth disorders andhemophilia. These vectors contain nucleic acid sequences coding forproteins or RNA. The sequences can encode for insulinlike growth factorI, insulin-like growth factor II, insulin growth factor binding protein,growth hormone, growth hormone release hormone, androgen receptors,mutant androgen receptors or derivatives thereof, apolipoprotein A-I,lipoprotein lipase, or the VLDL-receptor, nerve growth factor, or brainderived neurotropic factors. These are only examples and are not meantto be limiting. "Receptor" as used herein includes natural receptors(i.e. , as found in a cell in vivo) as well as anything that binds alikeand causes compartmentalization changes in a cell.

The methods of treating disease of the present invention feature methodsfor establishing expression of protein or RNA in tissue byadministration of a vector. These methods of use of the above-referencedvectors comprises the steps of administering an effective amount of thevectors to a human, animal or tissue culture. The term "administering"or "administration" as used herein refers to the route of introductionof a vector or carrier of DNA into the body. The vectors of the abovemethods and the methods discussed below may be administered by variousroutes. In particular a preferred target cell for treatment is theskeletal muscle cell. The term "skeletal muscle" as used herein refersto those cells which comprise the bulk of the body's musculature, i.e.,striated muscle.

Administration can be directly to a target tissue or may involvetargeted delivery after systemic administration. The preferredembodiments are by direct injection into muscle or targeted uptake intomuscle after intra-venous injection. The term "delivery" refers to theprocess by which the vector comes into contact with the preferred targetcell after administration. Administration may involve needle injectioninto cells, tissues, fluid spaces, or blood vessels, electroporation,transfection, hypospray, iontophoresis, particle bombardment, ortransplantation of cells genetically modified ex vivo. Examples ofadministration include intravenous, intramuscular, aerosol, oral,topical, systemic, ocular, intraperitoneal and/or intrathecal.

The preferred means for administration of vectors described aboveinvolves the use of formulations for delivery to the target cell inwhich the vector is associated with elements such as lipids, proteins,carbohydrates, synthetic organic compounds, or in-organic compoundswhich enhance the entry of the vector into the nucleus of the targetcell where gene expression may occur. The term "formulation" as usedherein refers to non-genetic material combined with the vector in asolution, suspension, or colloid which enhances the delivery of thevector to a tissue, uptake by cells within the tissue, intracellulartrafficking through the membrane, endosome or cytoplasm into thenucleus, the stability of the vector in extracellular or intracellularcompartments, and/or expression of genetic material by the cell. In apreferred embodiment of the present invention the vector and formulationcomprises a nanoparticle which is administered as a suspension orcolloid. The formulation can include lipids, proteins, carbohydrates,synthetic organic compounds, or inorganic compounds. Examples ofelements which are included in a formulation are lipids capable offorming liposomes, cationic lipids, hydrophilic polymers, polycations(e.g. protamine, polybrine, spermidine, polylysine), peptide orsynthetic ligand recognizing receptors on the surface of the targetcells, peptide or synthetic ligand capable of inducing endosomal-lysis,peptide or synthetic ligand capable of targeting materials to thenucleus, gels, slow release matrices, salts, carbohydrates, nutrients,or soluble or insoluble particles as well as analogues or derivatives ofsuch elements. This includes formulation elements enhancing thedelivery, uptake, stability, and/or expression of genetic material intocells. This list is included for illustration only and is not intendedto be limiting in any way.

Another embodiment of the present invention features the above vectorswith coating elements that enhance expression as well as uptake by thecell. The term "coating" as used herein refers to elements, proteins ormolecules used to associate with the vector in order to enhance cellularuptake. In particular, coating includes a DNA initiation complex andhistones. The coating improves the stability of the vector, its entryinto the nucleus, and the efficiency of transcription. The term "DNAinitiation complex" as used herein refers to a complex containing aserum response factor, a transcription initiation factor and atransregulatory factor. The serum response factor is attached to orinteracts with the serum response element within the promoter region ofthe vector. The transcription initiation factor and the transregulatoryfactor then interact with the serum response factor and the promoter, inparticular the TATA box within the promoter, to form a stable DNAcomplex. The term "histone" as used herein refers to nuclear proteinswhich associate with and/or bind to DNA, e.g., a vector. The histonescan bind specifically or non-specifically to the DNA.

The term "effective amount" as used herein refers to sufficient vectoradministered to humans, animals or into tissue culture to produce theadequate levels of protein or RNA. One skilled in the art recognizesthat the adequate level of protein or RNA will depend on the use of theparticular vector. These levels will be different depending on the typeof administration and treatment or vaccination.

The methods for treating diseases as disclosed herein includes treatmentwith biological products (specifically proteins as defined above) inwhich the disease being treated requires the protein to circulatethrough the body from the general circulation. For example, disorderswhich might be treated by the present invention include chronic pain byexpression of endorphin or enkephalins, anemia by expression oferythropoietin, hemophilia by expression of appropriate clotting factors(specifically factor IX for treatment of hemophilia B, factor VIII fortreatment of hemophilia A), failure of lactation by expression ofprolactin, osteoporosis by expression of IGF-I or its binding proteins,immune deficiencies by expression of cytokines, lymphokines orappropriate colony stimulating factors, or metastatic cancer by theexpression of interferon β or thrombospondin. The selection of theappropriate protein to treat various diseases will be apparent to oneskilled in the art.

In treating disease, the present invention provides a means forachieving: (1) sufficiently high levels of a particular protein toobtain a therapeutic effect; (2) controlled expression of product atlevels which are sufficient for therapeutic effect and lower than thetoxic levels; (3) controlled expression in certain tissues in order toobtain reproducible pharmacokinetics and levels of gene expression; and(4) delivery using clinically and pharmaceutically acceptable means ofadministration and formulation rather than transplantation ofgenetically engineered and selected cells.

In doing so, the present invention provides significant advances overthe art. First, promoters from viral genomes and viral vectors whichwere used to obtain high level expression in tissue, were not able toprovide controlled expression. Second, promoters from varioustissue-specific genes which were used to obtain controlled expression intransgenic animals and animal models of gene therapy did not have asufficiently high level of expression to obtain therapeutic effect. Inaddition, in treating diseases with the present invention, the abilityto raise antibodies against protein products does not reflect theability to achieve controlled expression of proteins within thetherapeutic range.

A sixth related aspect of the present invention features a method ofgene replacement for inherited genetic diseases of muscle. This methodincludes the transfection of muscle cells with the above-referencedvectors.

In a seventh aspect, the present invention features a method forinducing an immunogenic or immunological response by transfecting cellswith the above referenced vectors. The nucleic acid cassette may containnucleic acid sequences coding for proteins or other factors which mightproduce an immunogenic or immunological response. This would includeformation of a vaccine. The nucleic acid cassette can contain geneticmaterial that encodes for microbial proteins. This includes geneticmaterial coding for a bacterial protein, a viral protein, a fungalprotein, a yeast protein, or a parasitic protein. Examples of proteinswhich might be expressed include proteins from Human ImmunodeficiencyVirus, Cytomegalovirus, Respiratory Syncytial Virus, Influenza Virus,Hepatitis Virus (A,B,C,D), pneumococcus, meningococcus, streptococcus,staphylococcus, heat stable enterotoxin, heat labile enterotoxin,pneumocystitis, the pathogen of Lyme disease, aspergillus, candida, andmalaria. This is only an example and is not meant to be limiting.

The genetic material which is incorporated into the cells from the abovevectors can be any natural or synthetic nucleic acid. For example, thenucleic acid can be: (1) not normally found in the tissue of the cells;(2) normally found in a specific tissue but not expressed atphysiological significant levels; (3) normally found in specific tissueand normally expressed at physiological desired levels; (4) any othernucleic acid which can be modified for expression in skeletal musclecells; and (5) any combination of the above. In addition to the geneticmaterial which is incorporated into tissue, the above reference is alsoapplicable to genetic material which is incorporated into a cell.

Other features and advantages of the invention will be apparent from thefollowing detailed description of the invention in conjunction with theaccompanying drawings and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of the chicken skeletal-actin gene whichincludes location of unique restriction sites.

FIG. 2 illustrates the transcriptional domain of the avian skeletalα-actin gene and the contiguous noncoding region where transcriptionterminates.

FIG. 3 is a schematic representation of a myogenic vector system.

FIG. 4 is a schematic diagram of skeletal α-actin/insulin like growthfactor-I hybrid genes

FIG. 5 shows fast myosin light chain 3'UTR potentiates CAT activity inavian primary myoblasts, and substitutes for the skeletal actin 3'UTR.

FIGS. 6A and 6B show fast myosin light chain 3'UTR potentates CATactivity in Sol 8 and C₂ C₁₂ myoblasts, and substitutes for the skeletalactin 3'UTR.

FIG. 7 shows the change in body weight of diabetic rats treated withIGF-I containing MVS.

FIG. 8 shows the change in the weight of the gastocnemius muscle (thesite of injection) of diabetic rats treated with IGF-I containing MVS.

FIG. 9 shows the product amplified from IGF-I specific primers of cDNAgenerated from MVS-IGF-I injected mouse muscle.

FIG. 10 shows the change in plasma glucose levels of diabetic ratstreated with IGF-I containing MVS.

FIG. 11 shows a diagrammatic representation of a plasmid used to screenfor tissue-specific 3'UTR sequences.

FIG. 12 is a schematic representation of a regulatable vector systemusing a Vitamin D receptor.

FIG. 13 is a schematic representation of a regulatable vector systemusing a chimeric receptor.

FIGS. 14A-1 and 14A-2 show the DNA and amino acid sequences of the wildtype and mutant DNAs. The cytosine at position 2636 was missing in themutant DNA, therefore, a shifted reading frame was created and a stopcodon was generated 36 nucleotides downstream of the C-2636 deletion. Aschematic structure of the wild type and UP-1 receptors is alsopresented with a depiction of the 12 C-terminal amino acids unique tothe mutant receptor. Conserved and structurally similar amino acids aremarked by an apostrophe or asterisk, respectively.

FIG. 15 shows DNA sequence analysis of UP-1 identified a singlenucleotide deletion at base 2636. Thus mutation results in a shift ofthe reading frame which generates a stop codon 36 nucleotidesdownstream. As a result, the wild type receptor is truncated by 54authentic amino acids and 12 novel amino acids are added at theC-terminus.

The drawings are not necessarily to scale, and certain features of theinvention may be exaggerated in scale and shown in schematic form in theinterest of clarity and conciseness.

DETAILED DESCRIPTION OF THE INVENTION

The following are examples of the present invention using the regulatoryelements of myogenic genes to construct vectors for specific nucleicacid expression in various tissues. These examples are offered by way ofillustration and are not intended to limit the invention in any manner.

The following are specific examples of preferred embodiments of thepresent invention. These examples demonstrate how the expression vectorsystems of the present invention can be used in construction of variouscellular or animal models, and how genes can be regulated by sequenceswithin such vectors. The utility of such vectors is noted herein and isamplified upon in co-pending application by Schwartz et al., entitled"Myogenic Vector Systems," supra, and such sections (including drawings)are hereby specifically incorporated by reference herein.

Below are provided examples of specific regions of the 3'UTR and/or3'NCR regions of myogenic genes that can be used to provide certainfunctionalities to an expression vector, and thus within a transformedcell or animal containing such a vector. Those in the art will recognizethat specific portions of these regions can be identified as thatcontaining the functional nucleic acid sequence providing the desirableproperty, and such regions can be readily defined using routine deletionor mutagenic techniques or their equivalent. Such regions include thepromoter, enhancer, RNA stabilizing sequence, and cis- and transactingelements of a regulatable system. As noted herein, such controllingsegments of nucleic acid may be inserted at any location on the vector,although there may be preferable sites as described herein.

Isolation of Chicken Skeletal α-Actin Gene

The nucleic acid sequence of the skeletal α-actin gene has beencharacterized in chicken, rat, mouse and human. Fornwald et al, supra,Zak et al, supra, French et al, supra, Huetal, supra, Minty et al,supra. The primary sequences of the skeletal α-actin gene were deducedfrom overlapping cDNA clones. To obtain full genes, the cDNA clones wereused to screen genomic DNA.

For example, the 25 Kb EcoRI fragment of chicken genomic DNA isolatedfrom a lambda Charon 4A vector, contains the 6.2 Kb skeletal α-actingene on a single HindIII site of pBR322 is shown in FIG. 1. Chang et al.Mol. Cell. Biol. Vol 4:2498-2508 (1984). Nuclear transcription runoffswere used to map the transcriptional domain of the skeletal α-actin gene(FIG. 2). DNA probes which encompassed portions of the 5' noncoding,promoter coding, and the contiguous 3' noncoding regions were clonedinto M13 vectors which provided sense and antisense probes. Nucleiisolated from fibroblasts, myoblasts and day 19 embryonic muscle cellswere used in in vitro transcription assays to extend RNA transcriptswith radioactive tagged nucleotides. Labeled RNA hybridized to dottedDNA probes showed that transcription terminates approximately 1 kbdownstream of the skeletal α-actin gene's poly A addition site. This iswithin a 800 bp PvuII fragment between +2800 and +3600 nucleotides fromthe start of transcription.

The 3' UTR and/or 3' NCR can be isolated by restriction endonucleasesdigestion of the 6.2 Kb actin gene with blunt cutter NaeI, which cuts 30bp upstream of the translation termination codon TAA. HindIII releasesthe 3' most portion of the actin gene from the vector pBR322 (FIG. 3).The 3'UTR and 3'NCR were used to prepare DNA constructs. The skeletalα-actin promoter and DNA flanking sequences (at least 411 nucleotidesfrom the mRNA cap site) and DNA sequences extending through the skeletal5' noncoding leader, first intron and up to the initiation oftranslation ATG, converted to a NcoI cloning site at +196, was liberatedfrom a M13 double stranded DNA by XbaI and NcoI digestion, Klenow filledin and then linked into the XbaI and blunt SmaI sites of pBluescript IIKS. The NcoI site is regenerated by this cloning step. The 3'UTR and3'NCR on the 2.3 kb NaeI/HindIII fragment were directionally cloned intoa blunt EcoRV site and the adjacent HindIII site of the pBluescript IIKS vector cassette. The EcoRV and NaeI sites are destroyed. The restoredNcoI site was used to insert cDNA sequences encoding polypeptides.Another cloning vector was constructed by inserting the skeletal α-actinpromoter from -411 to -11 adjacent to the 3'UTR and 3'NCR. Thisexpression vector eliminates the first intron and the skeletal actin 5'leader sequence. These two vectors were used in preparing DNA constructsto test the efficacy of the 3'UTR and 3' NCR.

Expression Vector Construction Containing Human IGF-I Gene

Constructions containing the skeletal α-actin promoter were linked tothe human IGF-I cDNA (Seq. I.D. 6) by standard recombinant DNAtechniques as known in the art. Examples of a generalized expressionvector structure is shown in FIG. 3. Specific construction of anexpression vector with IGF-I is shown in FIG. 4. The construction wasmade so that the SV40 poly A addition site and the small t-intron werelinked to the 3'UTR of the IGF-I cDNA. The SV40 sequences were added toincrease the stability of nuclear IGF-I RNA transcripts. Since the SV40t-intron might not be entirely suitable in the expression of IGF-I inmuscle cells, five other vectors were made. The SK733 NcoI vectorcontains approximately 411 nucleotides of the skeletal α-actin promoter,the natural cap site, 5' untranslated leader and the first intron. AnNcoI site was engineered to create a unique insertion cloning site forthe cassette containing the IGF-I cDNA, in which the initiation ATG wasalso converted to an NcoI site. The SK733IGF-I construction utilizes itsown poly A site. An NaeI/HindIII fragment which incorporated theskeletal α-actin 3' UTR, poly A addition site, and terminating sequenceswas linked to SK202, SK733 NcoI, IGF-I and to SK733IGF-I which the IGF-Ipoly A site was deleted and replaced by that of skeletal α-actin. Inthis way IGF-I RNA transcripts containing the skeletal α-actin 3' UTRare stabilized and accumulate in skeletal muscle cells. In addition, byproviding contiguous 3' NCR, IGF-I is buffered against outside genomicsequences and is thus more protected from position effects, whenintegrated into the genome. In addition, by providing naturalterminating sequences, the additional regulatory sequences that mark thetranscriptional domain of skeletal α-actin prevent read throughtranscription, improve tissue specificity, developmental timing andtranscriptional activity. Presence of 3'NCR sequence allows for a singlecopy of the integrated vector to produce 40-500% of the transcriptionalactivity of the endogenous sequences.

Myogenic Cell Cultures

Primary chicken myoblast cultures from hind limbs of day 11 whiteleghorn chick embryos were developed according to the protocol describedin the art. Grichnik et al., Nucleic Acids Research vol. 14, pp.1683-1701 (1986) . Enriched myoblasts were plated at a density of 2×10⁵cells per 60 mm collagenized tissue culture dish.

Myogenic mammalian C₂ C₁₂ and Sol 8 cells (1×10⁵) were subcultured onto60 mm dishes one day before transfection.

DNA Transfer

Tissue culture cells were transfected with plasmid DNA by the calciumphosphate precipitation-glycerol shock protocol as known in the art.Wigler et al., Cell vol. 14, 725-731 (1978). A total of 10 μg of DNA wasused to transfect each 60 mm dish of tissue culture cells. Transfectionswere done in quadruplicate and with three different MVS-CAT-MLC plasmidpreparations to control for variations in DNA quality and platingdensity of cells.

CAT Assay

After transfection two populations of cells, coinciding with replicatingmyoblasts and post-fusion myotubes were harvested, and assayed for CATactivity as described in the art. Gorman et al., Molec. and Cell. Biol.,vol. 2, pp. 1044-1051 (1982). Cell pellets were lysed by repetitivefreeze thaw cycles in 50 μl of 250 mM Tris-HCl ph 7.5. The production ofacetylated ¹⁴ C! chloramphenicol (0.5 μCi per assay, 57.8 mCi/mMol) wasassayed for 90 minutes at 37° C. Acetylated chloramphenicol wasmonitored by autoradiography following thin layer chromatography onsilica gel plates. Separated acetylated chloramphenicol spots werequantitated by scanning on a Betagen phosphoimager screen. Data wasexpressed as the percentage of converted ¹⁴ C! chloramphenicol per μgcell protein. Protein concentration of cell extracts was determined bythe method of Bradford (Anal. Biochem., vol. 72, pp. 254-258 (1976)) ateach time point to insure uniformity in the assays.

Activity of Expression Vector Constructs

To determine the efficacy of actin promoter/gene IGF-I hybrid genes inmouse myogenic cells the expression vector was studied using these genesin the background of mammalian C₂ C₁₂ myoblasts by making a populationof stable transfected C₂ C₁₂ myoblasts. The altered IGF-I expressionlevels were directly evaluated in these stable myoblast cell lines. EachIGF-I construction (FIG. 4) was co-transfected with the drug selectablevector EMSV-Hygromycin into mouse C₂ C₁₂ cells. After two weeks ofselection, a population of stable myoblasts was selected. A populationof C₂ C₁₂ myoblasts stably transfected only with EMSV-Hygromycin servedas the controls. Visual inspection of the transfected myoblast revealedseveral insights into the role of IGF-I on muscle cell differentiationthat would not be obvious in transgenic mice. In general all of themyogenic cell lines containing IGF-I genes caused myoblasts in growthmedia (10% fetal calf serum) to replicate more extensively thancontrols. Changing culture medium to 2% horse serum initiates thedifferentiation process. In the process, control C₂ C₁₂ myoblasts fuseto form multinucleated myotubes over a period of four days. At the samecell density per culture dish, myoblasts containing SK733IGF-I,SK202IGF-I-SK, SK733IGF-I-SK1 and SK733IGF-I-SK2 fused at leasttwo-to-three days earlier than C₂ C₁₂ or EMSV-Hygromycin controlmyoblasts.

In order to study the steady state accumulation of IGF-I MRNA in C₂ C₁₂myoblasts, equal amounts of total cellular RNA was isolated from stablytransfected C₂ C₁₂ myoblasts grown in growth media ("G") ordifferentiation media ("D"). The RNA was electrophoretically separatedon denaturing agarose gels, transferred onto nylon filters and probedwith uniformly ³² p labeled full length human IGF-I cDNA under standardhybridization techniques. The intensity of the autoradiographic signalon X-ray film provides a relative measure of mRNA accumulation, anoverall index of combined transcriptional activity and mRNA stability ofthe expression vectors. The IGF-I mRNA in vector, SK202IGF-I-3'SVa didnot accumulate in myotubes above myoblast levels. This is a typicalexpression activity. The SK733IGF-I vector contains the IGF-I 3'UTR. TheIGF-I MRNA from this vector accumulated in myotubes but at levelssubstantially lower than SK202IGF-I-SK or SK733IGFI-SK2. These later twovectors contain the skeletal actin 3'UTR and 3'NCR. Since, the primarydifference in these vectors is the 3'UTR, the increased stabilization ofthe MRNA transcripts due to the skeletal 3'UTR accounts for about a100-!fold difference in MRNA content.

Measurement of Secreted Levels of IGF-I from IGF-I Gene Delivery by theExpression Vector

In order to measure the amount of IGF-I synthesized and secreted intothe media, differentiated myotube cultures were grown in minimal media(DMEM and 0.05% bovine serum albumin, RIA grade). SK733IGF-I-SK2 is themost effective construction to express IGF-I in muscle cells. IGF-I wasassayed by both radioimmunoassays of tissue culture media and byimmuno-peroxidase staining of cells. We have found increased levels ofIGF-I during the fusion of several of our muscle cultures. Thecomparison of levels from different expression vectors are shown inTable I. In control cultures, the level of IGF-I was in the range of0.2-0.5 ng/ml. In comparison, vector SK733IGF-I-SK2 has levels of IGF-Iat least one hundred times greater.

                  TABLE I                                                         ______________________________________                                        IGF-I Levels in Stably transfected C.sub.2 C.sub.12 Myoblasts                                IGF-I                                                          Construction   (ng/ml of media/4 days)                                        ______________________________________                                        SK202IGF-I-3'SVa                                                                             4.4                                                            SK733IGF-I     3.8                                                            SK733IGF-I-SK2 79.0                                                           Control C.sub.2 C.sub.12                                                                     0.5                                                            ______________________________________                                    

In a similar manner, immunoperoxidase staining of myogenic culturesrevealed the increased, production of immunological reactive IGF-I instable transfected myoblasts but not in the control EMSV-Hygromycintransfected myoblasts or in perfusion C₂ C₁₂ cells. Antibodies againstthe A and D regions were used at dilutions of 1:1000. All of thetransfected lines including SK202IGF-I were positively immunoperoxidasestained. Thus, it is clear that enhanced levels of IGF-I are beingsynthesized and exported from the stable myoblasts.

Determination of MRNA Stability in Muscle Cell Culture

The rate of measuring mRNA degradation in primary avian myogeniccultures containing well differentiated myotubes was measured by anextended pulse-chase method using ³ H! uridine. Total RNA in muscle cellcultures was labeled to equilibrium by a 48-hour incubation in mediacontaining 0.2 mCi/ml of ³ H! uridine starting on day 3 after platingmyoblasts. Under these conditions significant label was incorporatedinto the most stable of the contractile mRNAs. After labeling, the cellswere washed in DMEM and the ³ H! uridine chase by incubating cells inDMEM containing 10 mM uridine and 10 mM cytidine for two hours and thenchanged to DMEM, 10% horse serum, 5% chick embryo extract, 1 mM uridineand 1 mM cytidine for the duration of the experiments. No significantdifferences were observed in the specific activity of the labeled RNArepresented mostly by ribosomal RNA over a three-day period. This isconsistent with previous reports on ribosomal RNA stability in growingcells (Abelson, H. et al., Cell vol. 1, pp. 162; 1974) and in musclecells (Krauter, K. S.; Soerio, R. and Nadal-Ginard, J. Mol. Biol., vol.134, pp. 727-741; 1979).

RNA was isolated from these cultures at various times after the chase.To measure the relative levels of specific tritiated mRNAs, DNA probesto the untranslated regions of the actin mRNAs and to the coding regionsof the other mRNA were used. These probes were bound to nylon filters,hybridized with ³ H!-RNA at 1×106 cpm/ml, and washed and assayed asdescribed in the art. Zhu et al., J. Cell Biology, Vol. 115, pp. 745-754(1991). Quantitation was done by direct counting of ³ H!-RNA bound tothe nylon membrane, and expressed as a percentage of hybridized counts.Table II provides a summary of the kinetic hybridization assays.

                  TABLE II                                                        ______________________________________                                        Half-lives of Muscle and Non-Muscle mRNAs in                                  Primary Muscle Cell Cultures                                                  mRNA              Half-life (hours)                                           ______________________________________                                        Skeletal α-actin                                                                          19.4 +/- 2.4                                                Cardiac alpha actin                                                                             13.5 +/- 1.6                                                Beta actin         8.4 +/- 1.1                                                Fast Myosin light chain 1/3                                                                     60                                                          Cardiac Tropinin C                                                                              14.7 +/- 1.2                                                GAPDH             10.7 +/- 1.4                                                ______________________________________                                    

Measurement of the Stability IGF-I Hybrid 3'UTR Transcripts in MuscleCells

The steady state levels of different mRNAs reflect the balance betweenthe rate of synthesis of new mRNA and the rate of mRNA degradation. Thismeasurement was used to determine the ability of muscle specific 3'UTRto impart MRNA stability. Hybrid IGF-I constructs as described abovewere stably transfected into myogenic C₂ C₁₂ myoblasts, as shown above.These were challenged with a transcription blocker actinomycin D (8μg/ml) added to the culture media of differentiated myotubes. MessengerRNA stability was monitored by assessing the amount of residual mRNAremaining after transcriptional block, by RNA blotting with a ³² P!labeled human insulin-like growth factor I CDNA probe.

Construct SK733 IGF-I-3'SK2 showed substantial amounts of RNA indicatingenhanced stability 12 hours after actinomycin D addition. ConstructSK202IGF-I-3'SVa showed minimal amounts of RNA 8 hours after actinomycinD addition. This can be contrasted with the lack of stability of SK733IGF-I which diminished by 4 hours after actinomycin D addition.

Assay of Expression Vector Activity of Hybrid Constructs Containing theFast Myosin Light Chain 1/3 3'UTR

The sequence of the chicken skeletal muscle light chain 1/3 (MLC)untranslated region is 342 nucleotides in length (Nabeshima, Y. et al.,Nature, vol. 308, pp. 333-338; 1984). Oligonucleotides encoding thebeginning (5'GAGGACGTCCCCAG; Sequence I.D. No. 3) of the 3'UTR and theterminal 3'UTR sequence (5' GTCATTTAGGGACAACAG; Sequence I.D. No. 4)were used in a polymerase chain reaction to synthesize the intact MLC3'UTR. This was reductively subcloned into the Eco RV site in thecloning cassette of pBluescript II SK (+/-) phagemid. Verification ofthe MLC 3'UTR was done by dideoxy sequencing using T3 and T7 primeroligos. The plasmid was linearized with Pst I, treated with T4polymerase, and then released by digestion with Kpn I. An expressiontest vector was constructed which contained the bacterial Tn9 reportergene chloramphenicol acetyl transferase, linked downstream of theskeletal α-actin promoter, 5' cap, leader and the first intron, asdescribed above. In this vector, a portion of the bluescript II cassette(HindIII to Kpn-T) was cloned after the termination codon of CAT. Thisprovided restriction sites to clone in different 3'UTR sequences. MLC3'UTR was directionally cloned into the blunt ClaI site and the stickyended KpnI site. Taking advantage of MLCs unique Eco RI site that isasymmetrically placed towards the 5' end of the UTR, the appropriatelyoriented constructions were selected. In a similar way, the skeletal3'UTR and the SV40 t-intron 3'UTR poly A addition sequences were clonedadjacent to the end of the CAT reporter gene in the expression vector.The recombinant clones were amplified in DH5 alpha bacterial cells andplasmids were purified from bacterial lysates by two cesium chloridedensity gradient centrifugations. Plasmid DNA used in transfections wereat least 50% form I circular DNA.

Stability of Muscle MRNA Species

Table II summarizes the stability of myogenic contractile protein mRNAsin comparison to the housekeeping glycolytic enzymes,glyceraldehyde-phosphate dehydrogenase, and the non-myogenic β-actinMRNA in well differentiated muscle cells in culture. Calculated MRNAhalf lives in Table II demonstrates that fast myosin light chain 1 mRNAwas the most stable of all the mRNAs examined with a calculatedt_(1/2) >60h. Skeletal α-actin with a t_(1/2) of 19.4h was considerablymore stable than the nonmuscle β-actin and GAPDH mRNA with t_(1/2) of 8and 10 hrs. It is known that β-actin is an unique actin isoform found inreplicating myoblasts and nonmyogenic cell types, but not in welldifferentiated myotubes (Hayward, L. J.; Zhu, Y. Y.; and Schwartz, R.J., J. Cell Biology, vol. 106, pp. 2077-2086; 1988).

The Skeletal α-Actin 3'UTR Increases the Half-Life of mRNA in MuscleCells

The functional role of 3'UTRs on influencing the half life of RNAtranscripts in muscle cells was determined. Several expression vectorscontaining different 3'UTRs cloned adjacent to the IGF-I translationtermination codon were used. In this type of analysis, IGF-I served as areporter gene, and actinomycin D was used to block transcription instable C₂ C₁₂ muscle cell lines. Time RNA samples taken after theaddition of actinomycin D were probed with labeled human IGF-I cDNA.Transcripts containing the natural IGF-I 3'UTR were found to turnoverrapidly with a half life of less than 1/2 hour. Transcripts containingthe skeletal a-actin 3'UTR showed a high level of stability,corresponding to at least a T_(1/2) of 18 hours. Even transcriptscontaining SV₄₀ and 3'UTR and poly A addition signals showed a reducedhalf-life of 8 hours. Stability of IGF-I constructs containing skeletalα-actin 3'UTR corresponded well with the half-life of the endogenousskeletal α-actin mRNA.

Comparison of Myosin Light Chain 3'UTR with Skeletal α-Actin 3'UTR inStimulating Vector Expression in Muscle Cells

To demonstrate that the 3'UTR of another myogenic restricted gene isequivalent to the skeletal α-actin 3'UTR in the expression vector, theMLC, with a half-life of 60 hours, was used to measure increasing geneexpression in muscle cells. As described above, DNA constructions whichlinked together the skeletal α-actin promoter and the MLC 3'UTR weremade. A comparison was made of the activity of: (i) SV2CAT, a standardfor an active promoter/enhancer; (ii) MVS-CAT with an SV40 3't-intron/poly A site; (iii) MVS-CAT with an skeletal α-actin 3'UTR; and(iv) MVS-CAT with an MLC 3'UTR. Four replicate transfections, for eachCAT construction, were assayed during replication (pre-fusion, 24 hr) orfollowing myoblast fusion (72 hr). In the case of constructs containingthe MLC 3'UTR, four sets of transfections were done with three differentplasmid constructions.

The role of the 3'UTR sequences was evaluated by assaying CAT enzymaticactivity as shown in a representative set of experiments in FIG. 5 andTable III. Vectors containing myogenic sequences increased CAT activityfollowing fusion as was observed for the endogenous skeletal α-actingene. Vectors containing the skeletal actin promoter (MVS 3'SV) wereapproximately 5 times more active than the SV2CAT vector followingmyoblast fusion. Substitution of the skeletal α-actin 3'UTR for the SV40UTR increased activity by about another 4 fold. The MLC 3'UTR providedanother two to three fold increase in activity over the skeletal α-actin3'UTR. Overall, MVS-CAT with the 3'UTR appropriately switched geneexpression activity during the transition from replication to fusion,and increased CAT activity by eight to tenfold over MVS-CAT 3'SV.

In FIG. 6, a similar degree of activity dependent upon the skeletal andMLC 3'UTRs in mammalian C₂ C₁₂ and Sol 18 myoblasts was observed. Themyosin light chain is even more effective than the skeletal α-actin3'UTR in potentiating gene expression activity in differentiated avianand mammalian muscle cells. As shown above, the myosin light chain 3'UTRis capable of being substituted for the skeletal 3'UTR.

                  TABLE III                                                       ______________________________________                                        Analysis of CAT Activity in Transfected Avian Myoblasts                                                       Stand.                                        Construct   MEAN CAT Activity (% Conv)                                                                        Dev.                                          ______________________________________                                        SV2CAT      (pre)       0.3         0.02                                                  (post)      0.4         0.1                                       MVS-CAT 3'SV                                                                              (pre)       1.3         0.17                                                  (post)      1.9         0.25                                      MVS-CAT 3'SK                                                                              (pre)       5.3         0.42                                                  (post)      7.8         1.04                                      MVS-CAT 3'MLC                                                                             (pre)       3.8         0.5                                       (clone 22)  (post)      15.5        0.6                                       (clone 45)  (pre)       3.25        0.2                                                   (post)      13.1        1.4                                       (clone 52)  (pre)       2.7         0.3                                                   (post)      20.2        8.7                                       ______________________________________                                    

Insertion of Expression Vectors into Transgenic Mice

Transgenic mice carrying SK202IGF-I-3'SVa or SK202IGF-I-SK weregenerated by standard oocyte injection (Brinster, et al, Proc. Natl.Acad. Sci. USA, vol. 82, pp. 4438-4442 (1958)) and bred to demonstratestable transmission of transgenes to subsequent generations. Transgenicswere identified by polymerase chain reaction or Southern genomic DNAblotting analysis from tail cut DNA. Transgenics were tested for musclespecific expression of the transferred IGF-I vector by RNA blotting oftotal RNA isolated from several tissues. Independent transgenic mouselines 5484, 5496, 5832, 5834 were generated with SK202IGF-I-3'SVa,containing the SV40 3' intron and poly A addition sequence. Mice fromthese strains were found to have weak expression primarily in hearttissue, but very low levels were found in skeletal muscle andnon-myogenic tissues such as the kidney and brain. Independenttransgenic mouse lines 3357, 3359 generated with SK733IGF-I-3'SK2. Micefrom these strains were found to have elevated expression levels ofIGF-I. These levels are comparable to the endogenous mouse α-actin geneactivity. These levels from SK733IGF-I-3'SK2 show at least 100-1000 foldgreater accumulation of IGF-I mRNA in comparison to the levels producedby the SK202IGF-I-3'SVa vector. The addition of the skeletal α-actin3'UTR and 3' flanking region allowed for a preferential increase inIGF-I RNA in skeletal muscle rather than cardiac. Thus, the 3'UTR and 3'NCR of skeletal α-actin have an important role in enhancing musclespecific gene expression.

Mice from these strains demonstrated increased muscle mass and reducedpercentages of body fat as compared to the parental types. The use ofhuman IGF-I in the mouse demonstrates the cross-species applicability ofthis particular gene.

In addition, by providing contiguous 3' NCR, IGF-I is buffered againstoutside genomic sequences and is thus more protected from positioneffects, when integrated into the genome. In addition, by providingnatural terminating sequences, the additional regulatory sequences thatmark the transcriptional domain of skeletal α-actin prevent read throughtranscription, improve tissue specificity, developmental timing andtranscriptional activity. Presence of 3'NCR sequence allows for a singlecopy of the integrated vector to produce 40-50% of the transcriptionalactivity of the endogenous sequences.

Somatic Gene Transfer to Skeletal Muscle In Vivo

To demonstrate an effect of the vectors of the present invention as usedin vivo gene therapy, vectors were injected into adult muscle for theexpress purpose of expression of a particular polypeptide. The growthhormone-deficient mouse strain, little, was used in these studies.Vector SK733IGF-I-SK2, or control vector SKSK, was pelleted bysedimentation, dried under vacuum and punctured into the quadricepmuscle (20 μg/pellet - 3 pellets/muscle) of 2 sets of 6 little mice. Theentire muscle from each animal that received an inoculation was removed2 weeks following introduction of the DNA and assayed for IGF-I proteinin the tissue. The amount of IGF-I in each tissue was assayed by using aradioisotopic assay. A slight yet significant (p>0.05) increase wasobserved in IGF-1 expression (Table IV), from 4.2 ng IGF-1/100 μg totalprotein of muscle lysate in mice with vector only (no IGF-1) to 6.9 ngIGF-1/100 μg total protein of muscle lysate in those with the vectorSK733IGF1-3'SK.

                  TABLE IV                                                        ______________________________________                                        IGF-I Levels in Tissues of MVS-Injected little MICE                           Mouse #  Strain    Plasmid    IGF-I (ng/100 ug)                               ______________________________________                                        776      little    PSKSK      4.2                                             777      little    PSKSK      4.2                                             778      little    PSKSK      4.5                                             779      little    PSKSK      3.9                                             780      little    PSKSK      3.9                                             781      little    PSKSK      4.2                                             Average                       4.15 + 0.21                                     782      little    pSK733IGFSK                                                                              4.5                                             783      little    pSK733IGFSK                                                                              6.3                                             784      little    pSK733IGFSK                                                                              8.2                                             785      little    pSK733IGFSK                                                                              6.9                                             786      little    pSK733IGFSK                                                                              8.4                                             787      little    pSK733IGFSK                                                                              7.0                                             Average                       6.88 ± 1.08                                  ______________________________________                                    

Intramuscular Injections of a IGF-I Myogenic Vector in Diabetic Rats

The effect of intramuscular injections of a muscle-specific DNA vector("MSV") carrying the human insulin-like growth factor-I ("IGF-1") ondiabetes-induced alterations in body and muscle weights, plasma glucoselevels and the MRNA level from the injected MSV-IGF-I was examined. AnIGF-I expressing MSV was chosen for this work since injections ofrecombinant IGF-I have been shown to have anabolic effects in a numberof models of cachexia.

Diabetes was induced in male Sprague-Dawley rats (175200 g) withintravenous injections of streptozotocin (STZ; 55 mg/kg) dissolved insodium citrate buffer (0.05 M, pH 4.5). Control non-diabetic animalswere age, weight and sex matched and received equal volume injections ofvehicle. Diabetes was confirmed by the onset of hyperglycemia,glucosuria, and reduced rate of growth. Three days following STZadministration, non-fasted animals were anesthetized with pentobarbital(50 mg/kg) and blood samples were obtained by cardiac puncture. Bloodwas transferred to EDTA-containing tubes, centrifuged at 3000×g for 15min and stored at -70° C. The gastrocnemius was injected bilaterallyfollowing direct visualization of the muscle via a cutaneous incision.The right gastrocnemius muscle of individual rats was injected witheither 0, 50, 200, or 800 μg of MSV in 200 μl of isotonic salinesolution. The contralateral (left) gastrocnemius received 200 Alinjections of isotonic saline. The MSV used in this series ofexperiments was Sk-733-IGF-I-Sk2 as described above. Six days followingintramuscular injection of muscle-specific vector, the animals weredeprived of food (12-16 hrs) followed by euthanization by decapitation.Blood was then collected and the entire gastrocnemius muscle was removed(dissection from tendon to tendon).

For the analysis of vector effects on body and muscle weight dosagegroups were matched on pre-vector injection body weight and onlydiabetic animals were included in the analysis. The plasma glucosecriteria for inclusion in the analysis was a non-fasting plasma glucoselevel greater than 300 mg/100 ml. Pre-vector injection body weights werematched by only including animals with body weights between 175-195 gm.For the analysis of vector effects on plasma glucose levels the groupswere matched on pre-vector injection plasma glucose levels.Intramuscular injections of MSV result in increased body weight (FIG. 7;Mean±SD; Vehicle Only=181.37±6.17; 50 μg=193.43±5.71; 200 μg=186.6±8.01;800 μg=191.14±7.54). This body weight increase is statisticallysignificant at the 50 and 800 μg, but not the 200 μg, dose level (apriori t-test: Control vs. 50 μg, t=3.57, df=12; Control vs. 200 μg,t=1.17, df 10; Control vs. 800 μg, t=2.29, df=12).

In addition to increasing body weight MSV injections also increase theweight of the vector injected gastrocnemius (FIG. 8; Mean±SD; VehicleOnly=1.00±0.08; 50 μg 1.10±0.07; 200 μg=1.07±0.03; 800 μg=1.09±0. 05)This increase in vector injected gastrocnemius weight is statisticallysignificant at the 50 and 800 μg, but not the 200 μg, dose level(apriori t-test: Control vs. 50 μg, t=2.32, df=12; Control vs. 200 μg,t=1.75, df 10; Control vs. 800 μg, t=2.32, df=12). The weight of thecontralateral gastrocnemius was also increased but this increase did notreach statistical significant (Mean±SD; Vehicle Only=1.00±0.07; 50μg=1.07±0.06; 200 μg=1.05±0.01; 800 μg=1.08±0.06; a priori t-test:Control vs. 50 μg, t=1.72, df=12; Control vs. 200 μg, t=1.43, df 10;Control vs. 800 μg, t=2.11, df=12).

The level of expression of the injected MSV-IGF-I construct was assessedby determining the level of IGF-I specific mRNA. Whole cell RNA isolatedfrom the injected and control, contralateral, gastrocnemius, was treatedwith DNAase and subjected to reverse transcription using oligo-dT as aprimer in order to generate cDNA replicas of mRNA. The cDNA was thanreacted with IGF-I specific primers in a polymerase chain reaction toestimate the level of expression of mRNA in the original muscle sample.The bands corresponding to IGF-I-specific primer amplified products areshown in FIG. 9.

These data indicate that the MSV IGF-I construct is being expressed atsignificant levels in the injected muscle. The control muscle showed noexpression of human IGF-I.

Relative to the Control group fasting plasma glucose levels in the 50 μgMSV dose group were significantly lower (FIG. 10; Mean±SD; VehicleOnly=277.14±113.65; 50 μg=155.42±37.54; 200 μg=224.06±89.21; 800μg=216.57±100.55 mg/100 ml). (apriori t-test: Control vs. 50 μg, t=3.23,df=12; Control vs. 200 μg, t=1.04, df 17; Control vs. 800 μg, t=1.09,df=16).

These findings indicate that intramuscular injections of MSV(SK-7331-IGF-I-SK2) reduce diabetic hyperglycemia and increase body andmuscle weight suggesting that MSV expression levels are sufficient totrigger an anabolic effect. The finding that the vector injected, butnot the contralateral, gastrocnemius significantly increases in weightsuggests a difference in local IGF-I concentration in the two muscles.

Expression of Human Factor IX by MVS in C₂ C₂ muscle cells

Muscle specific vector (SK-F.IX-SK) containing the full length factor IXsequence can be transiently expressed in C₂ C₁₂ cells. The C₂ C₁₂myoblasts and myotubes were transfected using CaPo₄ or lipofectin andthe human Factor IX secreted in the conditioned medium was analyzedusing an ELISA. The C₂ C₁₂ cells, purchased from the American TypeCulture Collection, were plated at a density of 0.5×10⁶ dish in a mediumcontaining DMEM with high glucose, 10%- FBS, and 1% penicillinstreptomycin. Cells were transfected as myoblasts at 24 h after platingor allowed to differentiate in medium with 2% horse serum andtransfected as myotubes a week after initial plating. Both myoblasts andmyotubes were transfected with 20 μg DNA either in saline, lipofectin(1:7 DNA:lipofectin), or CaPO₄ precipitates for 5 h in a serum freemedium. After transfection, cells were fed with DMEM containing 2% horseserum and the media was collected at 24, 40, 72, 96, 120, and 130 h forquantitation of human Factor IX.

The amount of human Factor IX secreted in the culture medium wasquantitated by a ELISA using a modification of the procedure describedby Kay et al. Kay et al., Human Gene Therapy vol. 3 pp. 641-647 (1992).Briefly, 96-well plates were coated with a monoclonal mouse anti-humanFactor IX antibody at a concentration of 2 μg/ul for 1 h at roomtemperature. Samples (50 μl) of conditioned media were than added andallowed to bind for 1 h at 37° C. This was followed by the applicationof a 1:10,000 dilution of a polyclonal rabbit anti-human Factor IXantibody. The antigen-antibody complex was recognized by a peroxidaseconjugated anti-rabbit IgG. The assay was developed with 3,3', 5,5',tetramethylbenzidine dihydrochloride (TMBD) and H₂ O₂ incitrate/phosphate buffer and the color changed measured at 405 nm.

As shown in Table V, no detectable levels of human Factor IX were found24-72 h after transfection in either mode of DNA delivery to themyoblasts. However, at 96 h after transfection a significant increase inFactor IX was observed in cells transfected with the CAPO₄ procedure(naked DNA 0.29 ng/100 μl, DNA:CaPO₄ 1.83 ng/100 μl). Factor IX levelsin this group increased further at 120 h (naked DNA 0.96 ng/100 μl,DNA:CaPO₄ 6.08 ng/100 μl) and then declined to the basal level at 130 h.No detectable Factor IX was found in cells transfected with DNAformulated in lipofectin. These data suggest that the human factor IXgene construct (SK-F.IX-SK) can be expression in C₂ C₁₂ myoblasts.

                  TABLE V                                                         ______________________________________                                        ELISA Detection of Factor IX in Cultured Myotubes                                        Expression time (h)                                                           24   40     72     96   120   136                                             Human Factor IX (ng/100 μl)                                     ______________________________________                                        Naked DNA    0.0    0.0    0.2  0.3  1.0   0.0                                DNA:CaPO.sub.4                                                                             0.2    0.0    0.0  1.8  6.1   0.0                                Lipofectin   0.2    0.1    0.1  0.3  2.2   1.3                                DNA:Lipofectin (1:7)                                                                       0.4    0.2    0.0  0.2  0.0   2.5                                ______________________________________                                    

Enhanced Vector Expression in Intact Muscle

Intact plasmid DNA in a sterile 20% sucrose solution (wt/vol) can beinjected into mature avian or mammalian muscle. Following a singleinjection the vector DNA is stable for at least 30 days as anon-integrated extrachromosomal circular DNA in muscle nuclei and, istranscriptionally active. Wolf et al., Science, vol. 247, pp. 1465-1468(1990). However, greater than 99% of the injected DNA is degraded inmuscle under the Wolff protocol (Wolff, et al, BioTechniques, vol. 11,pp. 4374-485, (1991)). This protocol can be improved by increasing theuptake of plasmid DNA into muscle and reducing vector degradation. Theprocedure of the present invention uses expression vector DNA coatedwith the relevant transcriptional regulatory factors, the human serumresponse factor and other human associated nuclear proteins, such ashistone, and transcription initiation factors to enhance uptake andstability. The regulatory proteins protect the DNA against musclenucleases and facilitate the uptake of the protein coated DNA intomyogenic nuclei.

The expression vector forms a protein/DNA complex by the sequencespecific binding of the serum response factor with the inner coreCCXXXXXXGG (where X can be either A or T; Sequence I.D. No. 5) of theserum response element and by the addition of histone. The interactionwith the inner core of the promoter facilitates myogenic cell typerestricted expression of the skeletal a-actin gene. The serum responsefactor, transcription initiation factor, transregulatory factor andhistones are added to the expression vector by an in vitro bindingreaction to form a reconstituted protein/DNA complex.

Coating the Expression Vector System

A specific formulation involves coating the vector with elements of thetranscription initiation complex and histone. This formulation is usedboth to enhance delivery of the vector to the cell and to enhanceexpression of the vector within the cell.

The following protocol was used to bacterially express and purify humanserum response factor (SRF). Plasmid PARSRF-Nde is a T7 polymerasevector (Studier, F. W. and Moffatt, J. Mol. Biol., vol. 189, pp 113-130(1986)) which produced full-length SRF protein upon IPTG(isopropyl-B-D-thiogalactopyranoside) induction. (Manak et al., Genesand Development vol. 4, pp. 955-967 (1990)). E. coli BL21 harboring theplasmid was grown at 37° C. to an OD₆₀₀ of 0.4 in TYP mediumsupplemented with ampicillin (50 μg/ml). Synthesis of SRF was theninduced with 1 mM IPTG for 2.0 hr, after which cells were spun down,washed once in TE buffer (10 mM Tris-HCl, 1 mM EDTA, pH 7.0) andresuspended in a 40X packed cell volume and dialyzed against (10 mMHEPES N-2 hydroxyethylpiperzine-N-2-ethansulfonic acid, pH 7.4!, 60 mMKCl, 1 mM 2-mercaptoethanol 0.5 mM EDTA, 0.5 mM phenylmethylsulfonylfluoride and 10% glycerol). Cells were disrupted on ice by sonication.The lysate was clarified by centrifugation (15,000×g for 20 min.) andthe high speed supernatant containing overexpressed SRF was stored at-80C. Partial purification of SRF was done as follows. A 10 ml amount ofthe lysate was applied to a 10 ml phosphocellulose column equilibratedwith column buffer (same as dialysis buffer as described above) and0.05% Nonidet P-40. The flow through fractions were collected andapplied to a 5-ml heparin agarose column. The column was washed with0.35M KC1 and SRF was eluted with 0.5M KC1. SRF was then dialyzed andstored at -80° C.

Approximately, a ratio by weight of 5 to 1 SRF protein to expressionvector DNA was allowed to incubate together in a solution containing 10mM. Tris-HCl (pH 8.0, 0.1 mM EDTA, 2 mM dithiothreitol, 5% glycerol plus100 mM KC1. The binding of SRF to the actin promoter has been verifiedby DNA binding assays and by nuclease footprint protection assays asshown in the art. Transcription initiation factors such as the TATA boxprotein (TBP) and other initiation factors such as TFIIB, E and F areeluted from purified HeLa cell nuclei by the protocol of Dignam et al.,Mol. Cell. Biol., vol. 10, pp. 582-598 (1983) with 0.42M KCl in theabove dialysis buffer. Nuclear lysates containing transcriptioninitiation factors are mixed together with the SRF-DNA plasmid at aratio of 10 parts protein to one part SRF-DNA to help form apreinitiation complex which is dialyzed for 24 hours. Finally, a crudehistone preparation which is stripped from HeLa nuclei in 6M urea, 2MNaCl is dialyzed against low salt dialysis buffer. The full complementof histone are slowly added to a final ratio of 1 to 1 (histone to theSRF-protein DNA complex) to form nucleosome particles over nonprotectedDNA. The addition of histone will protect regions of DNA to a greaterextent than naked DNA from cellular nucleases.

The nucleoprotein complex is then further formulated with a lipid base,nonaqueous base and/or liposomes for direct injection into muscle.Because of the abundance of specific transcription factors, whichcontain nuclear targeting sequences, expression vector DNA is readilydelivered, and taken up into muscle nuclei. The expression vector canalso be delivered as described below.

Selection of 3° Flanking Regions that Demonstrate Tissue-SpecificEnhancement of mRNA Stability in Liver or other Cells

Selection of 3' flanking regions, which incorporate 3'UTR and/or 3'NCR,from particular tissues, including liver, can be achieved throughscreening of 3' ends of DNA libraries using a plasmid designed to impartneomycin resistance to cells only when neo-r transcripts are stabilizedfor an extended period. The screening plasmid contains the followingelements orientated as depicted in FIG. 11. Constituitively expressedfrom the plasmid is the mutant steroid receptor described in the patentapplication U.S. Ser. No. 07/939246 by Vegeto et al., entitled "MutatedSteroid Hormone Receptors, Methods for Their Use and Molecular Switchfor Gene Therapy", and the selectable gene guaninephosphoribosyltransferase (GPT).

FIG. 2 shows the DNA and amino acid sequences of the wild type andmutant DXNAs. The cytosine at poisition 2636 was missing in the mutantDNA, therefore, a shifted reading frame was created and a step codon wasgenerated 36 nucleotides downstream of the C-2636 deletion. A schematicstructure of the wild type and UP-1 receptors is also presented with adepicition of the 12 C-terminal amino acids uniqute to the mutantreceptor. Conserved and structurally similar amino acids are marked byan apostrophe or asterisk, respectively.

DNA sequence analyis so of UP-1 identified a single nucleotide deletionat base 2636 (FIG. 2B). This mutation results in a shirft of the readingframe which generates a stop codon 36 nucleotides downstream. As aresult, the wild type receptor is truncated by 54 authentic amino acidsand 12 novel amino acids are added at the C-terminus.

In another position in the plasmid is the steroid responsive, GAL4sequence, linked to a tissue-specific promoter that drives transcriptionof the neomycin resistance gene that is modified at the 3' end to have acloning site for the 3' flanking region library sequences. Specifically,for selection of liver specific 3' flanking region sequences, theα-1-antitrypsin promoter is used to drive the neomycin resistance geneand the 3' flanking region sequences will be selected for in HPRT- HepG2cells.

Tissue specific 3' flanking region sequences derived from DNA librariesand sequences between 50 and 2000 base pairs are cloned into the cloningsite of the plasmid to generate test plasmids. Test plasmids are thantransfected into the cell type of desire using the CAPO₄ method as knownin the art. For liver specific sequences the cell type is HepG2. Initialscreening for the cells that have been transfected is in mediumcontaining 5×10⁻⁴ M hypoxanthine, 4×10⁻⁶ M aminopterin and 5×10⁻⁵ Mthymidine (HAT media). Non-transfected cells are killed in this mediumleaving only the transfected cells. To select for the ability of thelibrary fragments to establish RNA with an extended half-life thetransfected cells are initially treated with 0.1 μM RU486 for 6 hrs.RU486 treatment will induce expression from the GAL4-linked promoter ofthe neomycin resistance gene. 60 hrs after the RU486 treatment the cellsare treated with medium containing 2 mg/m of G418 for 24 hr. Only thosecells that have sufficiently long-lived mRNA producing the neomycinresistance product will survive this selection procedure.

The plasmids that are recovered from the selected cell population areanalyzed as to the nature of the 3' flanking regions and confirmed inadditional studies of RNA half life by methods known in the art. Whilethe example given here is for liver cells one skilled in the art willeasily recognize that any cell type may be substituted in order toobtain tissue-specific 3' flanking regions which stabilize MRNA. Inaddition, point mutations, deletions or insertions to the 3' flankingregions are acceptable in order to modify the 31 flanking region butstill retain or enhance the MRNA stability activity.

Administration

Administration as used herein refers to the route of introduction of avector or carrier of DNA into the body. Administration can be directlyto a target tissue or by targeted delivery to the target tissue aftersystemic administration. In particular, the present invention can beused for treating disease by administration of the vector to the body inorder to establishing controlled expression of any specific nucleic acidsequence within tissues at certain levels that are useful for genetherapy.

The preferred means for administration of vector and use of formulationsfor delivery are described above. The preferred embodiment is by directinjection using needle injection or hypospray.

The route of administration of any selected vector construct will dependon the particular use for the expression vectors. In general, a specificformulation for each vector construct used will focus on vector uptakewith regard to the particular targeted tissue, followed by demonstrationof efficacy. Uptake studies will include uptake assays to evaluatecellular uptake of the vectors and expression of the tissue specific DNAof choice. Such assays will also determine the localization of thetarget DNA after uptake, and establishing the requirements formaintenance of steady-state concentrations of expressed protein.Efficacy and cytotoxicity can then be tested. Toxicity will not onlyinclude cell viability but also cell function.

Muscle cells have the unique ability to take up DNA from theextracellular space after simple injection of DNA particles as asolution, suspension, or colloid into the muscle. Expression of DNA bythis method can be sustained for several months.

Delivery of formulated DNA vectors involves incorporating DNA intomacromolecular complexes that undergo endocytosis by the target cell.Such complexes may include lipids, proteins, carbohydrates, syntheticorganic compounds, or inorganic compounds. The characteristics of thecomplex formed with the vector (size, charge, surface characteristics,composition) determines the bioavailability of the vector within thebody. Other elements of the formulation function as ligand whichinteract with specific receptors on the surface or interior of the cell.Other elements of the formulation function to enhance entry into thecell, release from the endosome, and entry into the nucleus.

Delivery can also be through use of DNA transporters. DNA transportersrefers to molecules which bind to DNA vectors and are capable of beingtaken up by epidermal cells. DNA transporters contain a molecularcomplex capable of non-covalently binding to DNA and efficientlytransporting the DNA through the cell membrane. It is preferable thatthe transporter also transport the DNA through the nuclear membrane.See, e.g., the following applications all of which (including drawings)are hereby incorporated by reference herein: (1) Woo et al., U.S. Ser.No. 07/855,389, entitled "A DNA Transporter System and Method of Use,"filed Mar. 20, 1992; (2) Woo et al., PCT/US93/02725, entitled "A DNATransporter System and method of Use", (designating the U.S. and othercountries) filed Mar. 19, 1993; (3) continuation-in-part application byWoo et al., entitled "Nucleic Acid Transporter Systems and Methods ofUse", filed Dec. 14, 1993, assigned attorney docket number 205/012 butnot yet assigned a U.S. Ser. No.; (4) Szoka et al., U.S. Ser. No.07/913,669, entitled "Self-Assembling Polynucleotide Delivery System",filed Jul. 14, 1992 and (5) Szoka et al., PCT/US93/03406, entitled"Self-Assembling Polynucleotide Delivery System", (designating the U.S.and other countries) filed Apr. 5, 1993.

Transfer of genes directly into muscle has been very effective.Experiments show that administration by direct injection of DNA intomuscle cells results in expression of the gene in the area of injection.Injection of plasmids containing IGF-I results in expression of the genefor months at relatively constant levels. The injected DNA appears topersist in an unintegrated extrachromosomal state. This means oftransfer is the preferred embodiment.

Another preferred method of delivery involves a DNA transporter system.The DNA transporter system consists of particles containing severalelements that are independently and non-covalently bound to DNA. Eachelement consists of a ligand which recognizes specific receptors orother functional groups such as a protein complexed with a cationicgroup that binds to DNA. Examples of cations which may be used arespermine, spermine derivatives, histone, cationic peptides and/orpolylysine. one element is capable of binding both to the DNA vector andto a cell surface receptor on the target cell. Examples of such elementsare organic compounds which interact with the asialoglycoproteinreceptor, the folate receptor, the mannose-6-phosphate receptor, or thecarnitine receptor. A second element is capable of binding both to theDNA vector and to a receptor on the nuclear membrane. The nuclear ligandis capable of recognizing and transporting a transporter system througha nuclear membrane. An example of such ligand is the nuclear targetingsequence from SV40 large T antigen or histone. A third element iscapable of binding to both the DNA vector and to elements which induceepisomal lysis. Examples include inactivated virus particles such asadenovirus, peptides related to influenza virus hemagglutinin, or theGALA peptide described in the Skoka patent cited above.

Administration may also involve lipids. The lipids may form liposomeswhich are hollow spherical vesicles composed of lipids arranged inunilamellar, bilamellar, or multilamellar fashion and an internalaqueous space for entrapping water soluble compounds, such as DNA,ranging in size from 0.05 to several microns in diameter. Lipids may beuseful without forming liposomes. Specific examples include the use ofcationic lipids and complexes containing DOPE which interact with DNAand with the membrane of the target cell to facilitate entry of DNA intothe cell.

Gene delivery can also be performed by transplanting geneticallyengineered cells. For example, immature muscle cells called myoblastsmay be used to carry genes into the muscle fibers. Myoblast geneticallyengineered to express recombinant human growth hormone can secrete thegrowth hormone into the animal's blood. Secretion of the incorporatedgene can be sustained over periods up to 3 months.

Myoblasts eventually differentiate and fuse to existing muscle tissue.Because the cell is incorporated into an existing structure, it is notjust tolerated but nurtured. Myoblasts can easily be obtained by takingmuscle tissue from an individual who needs gene therapy and thegenetically engineered cells can also be easily put back with outcausing damage to the patient Is muscle. Similarly, keratinocytes may beused to delivery genes to tissues. Large numbers of keratinocytes can begenerated by cultivation of a small biopsy. The cultures can be preparedas stratified sheets and when grafted to humans, generate epidermiswhich continues to improve in histotypic quality over many years. Thekeratinocytes are genetically engineered while in culture bytransfecting the keratinocytes with the appropriate vector. Althoughkeratinocytes are separated from the circulation by the basementmembrane dividing the epidermis from the dermis, human keratinocytessecrete into circulation the protein produced.

Delivery may also involve the use of viral vectors. For example, anadenoviral vector may be constructed by replacing the E1 region of thevirus genome with the vector elements described in this inventionincluding promoter, 5'UTR, 3'UTR and nucleic acid cassette andintroducing this recombinant genome into 293 cells which will packagethis gene into an infectious virus particle. Virus from this cell maythen be used to infect tissue ex vivo or in vivo to introduce the vectorinto tissues leading to expression of the gene in the nucleic acidcassette.

The chosen method of delivery should result in expression of the geneproduct encoded within the nucleic acid cassette at levels which exertan appropriate biological effect. The rate of expression will dependupon the disease, the pharmacokinetics of the vector and gene product,and the route of administration, but should be between 1-1000 mg/kg ofbody weight/day. This level is readily determinable by standard methods.It could be more or less depending on the optimal dosing. The durationof treatment will extend through the course of the disease symptoms,possibly continuously. The number of doses will depend upon diseasedelivery vehicle and efficacy data from clinical trials.

Cell Transfection and Transformation

One embodiment of the present invention includes cells transfected withthe vectors described above. Once the cells are transfected, thetransformed cells will express the protein or RNA encoded for by thenucleic acid cassette. Examples of proteins include, but are not limitedto polypeptide, glycoprotein, lipoprotein, phosphoprotein, ornucleoprotein. The nucleic acid cassette which contains the geneticmaterial of interest is positionally and sequentially oriented withinthe vectors such that the nucleic acid in the cassette can betranscribed into RNA and, when necessary, be translated into proteins orpolypeptides in the transformed cells.

A variety of proteins can be expressed by the sequence in the nucleicacid cassette in the transformed epidermal cells. Those proteins whichcan be expressed may be located in the cytoplasm, nucleus, membranes(including the plasmalemma, nuclear membrane, endoplasmic reticulum orother internal membrane compartments), in organelles (including themitochondria, peroxisome, lysosome, endosome or other organelles), orsecreted. Those proteins may function as intracellular or extracellularstructural elements, ligand, hormones, neurotransmitter, growthregulating factors, differentiation factors, gene-expression regulatingfactors, DNA-associated proteins, enzymes, serum proteins, receptors,carriers for small molecular weight organic or inorganic compounds,drugs, immunomodulators, oncogenes, tumor suppressor, toxins, tumorantigens, or antigens. These proteins may have a natural sequence or amutated sequence to enhance, inhibit, regulate, or eliminate theirbiological activity. Specific examples of proteins to be expressedinclude those described above in reference to the term nucleic acidcassette.

In addition, the nucleic acid cassette can code for RNA. The RNA mayfunction as a template for translation, as an antisense inhibitor ofgene expression, as a triple-strand forming inhibitor of geneexpression, as an enzyme (ribozyme) or as a ligand recognizing specificstructural determinants on cellular structures for the purpose ofmodifying their activity. Specific examples include RNA molecules toinhibit the expression or function of prostaglandin synthase,lipooxenganse, histocompatibilty antigens (class I or class II), celladhesion molecules, nitrous oxide synthase, β₂ microglobulin, oncogenes,and growth factors.

The compounds which can be incorporated are only limited by theavailability of the nucleic acid sequence for the protein or polypeptideto be incorporated. One skilled in the art will readily recognize thatas more proteins and polypeptides become identified they can beintegrated into the vector system of the present invention and expressedin animal or human tissue.

Transfection can be done either by in vivo or ex vivo techniques. Forexample, muscle cells can be propagated in culture, transfected with thetransforming gene, and then transplanted into muscle tissue.Alternatively, the vectors can be administered to the cells by themethods discussed above.

Regulatable Expression Vector System

Under certain circumstances, it is desirable to control the vector'stranscriptional activity over time and to switch gene transcription onand off. It may also be important that the regulation of the expressionvector be controlled by natural inducer products that are neitherconsidered toxic to humans nor are immunogenic. Two nonrestrictingexamples of different Vitamin D regulatory systems are shown in FIGS. 12and 13.

The cellular concentration of Vitamin D receptor (VDR) in muscle can beincreased through the expression vector by injecting a hybrid skeletalactin VDR gene that would be under control of the actin promoter and the3'UTR stabilizing sequences. The target, SEQ. ID. No. 2, is constructedto contain synthesized multimers of the Vitamin D regulatory element(VDRE). This target is linked to a minimal Herpes Simplex Virus (HSV)thymidine kinase promoter. Transcriptional activity emanating from theTK promoter is regulated by the presence of VDR and coactivated by theligand, Vitamin D. Any polypeptide sequence cloned in tandem to the HSVpromoter, as a cDNA, is driven from the target vector when Vitamin D isintroduced into the muscle cells. The hybrid actin VDR gene and thetarget vector are linked on the same plasmid or coinjected on separateplasmids. Premeasured levels of Vitamin D are administered by drinking aglass of milk or taking a Vitamin D pill. The levels are used toactivate transcription of the target vector. Taking the ligand on everyother day, will oscillate the promoter activity. Removal of the ligand,Vitamin D, from the diet down regulates or represses transcription fromthe target vector. One skilled in the art will recognize that otherreceptors and binding domains can be used.

Methods of Use Treatment with Growth Hormone

Growth hormone is normally produced and secreted from the anteriorpituitary and promotes linear growth in prepuberty children. Growthhormone acts on the liver and other tissues to stimulate the productionof insulin like growth factor I. This factor is, in turn, responsiblefor the growth promoting effects of growth hormone. Further, this factorserves as an indicator of overall growth hormone secretion. Serum IGF-Iconcentration increases in response to endogenous and erogenousadministered growth hormone. These concentrations are low in growthhormone deficiency. Insulin-like growth factors are one of the keyfactors that potentiate muscle development and muscle growth. Myoblastsnaturally secrete IGF-I/IGF-II as well as its cognate binding proteinsduring the onset of fusion. This process coincides with the appearanceof muscle specific gene products. In terminally differentiated muscle,signals propagated from passive stretch induced hypertrophy induce theexpression of IGF genes. Many of the actions of IGFs on muscle resultfrom interactions with the IGF-I receptor. The intramuscular injectionof an expression vector containing the sequence for IGF-I (for exampleSK 733 IGF-I Sk2) can be used to treat growth disorders. Vectors aredesigned to control the expression of IGF-I in a range of 100-400 ng/ml.Since intramuscular expression of vectors leads to expression of theproduct encoded by the nucleic acid cassette for several months, thismethod provides a long-term inexpensive way to increase systemic bloodconcentration of IGF-I in patients with growth hormone deficiency.

Treatment of Dystrophic Muscle Disease

Muscular dystrophies are among the most frequent of inherited geneticdisorders. Muscular dystrophies are usually not immediately fatal butdevelop progressively. Molecular genetic analysis has identifiedmutations in at least a dozen genes that alone or in combination resultin muscular dystrophic symptoms. Presently there is no effective curefor these diseases and therapy is devoted to management of acutesymptoms. Expression of the non-mutated counterpart of these genes inthe muscle cells of patients with muscular dystrophy alleviates some ofthe debilitating symptoms.

The expression vector of the present invention is ideally suited for thetreatment of muscle disorders including almost all forms of musculardystrophy. The present vector system will be able to express high levelsof the following genes specifically in muscle tissue; the full lengthDuchenne's muscular dystrophy gene (dystrophin), the related sequence ofthe gene responsible for Becker's muscular dystrophy; myotonin proteinkinase; alphα-subunit of Na+channels; the 50 kd-dystrophyn associatedglycoprotein; myophosphorylase; phosphofructokinase; acid maltase;glycogen debrancing enzyme; phosphoglycerate kinase; phosphoglycerolmutase; lactate dehydrogenase; and carnitine palmitoyl transferase. Theappropriate gene for the particular afflicted individual can bedetermined through genetic screening as known in the art.

Administration of the vectors can be intravenously, through directinjection into the muscle or by any one of the methods described above.Dosages will depend on the severity of the disease and the amount ofdosage is readily determinable by standard methods. The duration oftreatment will extend through the course of the disease symptoms whichcan be continuously.

Treatment of Muscle Atrophy Due To Age

Growth hormone levels decline with increasing age. The levels in healthymen and women above age of 55 are approximately one third lower than thelevels in men and women 18 to 33. This is associated with a decrease inthe concentration of IGF-I. The decline in growth hormone and IGF-Iproduction correlate with the decrease in muscle mass, termed senilemuscle atrophy, and increase in adiposity that occur in healthy humansubjects. Administering growth hormone three times a week to healthy 61to 81 year old men who had serum levels below those of healthy youngermen increased the serum IGF-I levels to within the range found in younghealthy adults. This increase level led to increased muscle mass andstrength and reduced body fat. The secretion of growth hormone isregulated by a stimulatory (growth hormone releasing hormone) and aninhibitory (somatostatin) hypothalamic hormone.

The convenient cloning sites in the expression vectors of the presentinvention are used to construct vectors containing human growth hormoneCDNA sequence, the human growth hormone releasing hormone (GHRH), orIGF-I. This versatility is important since the GHRH, GH, and IGF-I,while having equivalent desired effects on muscle mass, may havedifferent side effects or kinetics which will affect their efficacy. Theexpression of the growth factor releasing hormone might be moreadvantageous than the expression of either IGF-I or the growth hormonevectors transcripts. Since GHRH is reduced in the elderly it appears tobe responsible for the lack of GH secretion rather than the anteriorpituitary capability of synthesizing growth hormone, thus the increasedexpression of GHRH from muscle would increase GHRH levels in thesystemic blood system and can allow for the natural diurnal secretionpattern of GH from the anterior pituitary. In this way, GHRH could actas the natural secretogogue, allowing for elevated secretion or releaseof GH from the hypothalamus of the elderly.

Thus, the application of vector systems described herein to expressinsulin-like growth factors through the injection of the SK 733 IGF-ISk2 vector, vectors expressing HG, or GHRH into adult muscle of theelderly is a long-term inexpensive way to increase systemic bloodconcentration of IGF-I in the elderly.

Administration of the vectors can be intravenously, through directinjection into the muscle or by any one of the methods described above.Dosages will depend on the severity of the disease and the amount ofdosage is readily determinable by standard methods. The duration oftreatment will extend through the course of the disease symptoms whichcan be continuously.

Treatment of Human Muscle Atrophies Induced by Neurological Dysfunction

Insulin-like growth factors are also known neurotrophic agents whichmaintain neuronal muscular synapses, neuron integrity, and neuronal celllife under neurodegenerative conditions. Since the expression vectordriven genes are relatively insensitive to the innervation state of themuscle, they provide a direct and rather broad application for remedyingcertain kinds of human muscle atrophies caused by spinal cord injuriesand neuromuscular diseases caused by drugs, diabetes, Type I disease,Type II diabetes, genetic diseases such as CHACOT-marie-tooth disease orcertain other diseases. Moreover, IGF-I secretion can induce neuriteoutgrowth. In this treatment, the product of the vector acts as aneurotrophic agent secreted from injected muscle and as a hypertrophicagent to maintain muscle integrity.

Administration of the vectors can be intravenously, through directinjection or by any one of the methods described above. Dosages willdepend on the severity of the disease and the amount of dosage isreadily determinable by standard methods. The duration of treatment willextend through the course of the disease symptoms which can becontinuously.

Treatment of Atherosclerotic Cardiovascular Diseases

Atherosclerotic cardiovascular disease is a major cause of mortality inthe United States and the world. The atherosclerotic plaque, the basicunderlying lesion in atherosclerosis, contains cholesterol esters thatare derived from circulating lipids. These circulating lipids areessential to the development of atherosclerosis. The plasmaconcentration of high density lipoprotein (HDL) is inversely related tothe propensity for developing atherosclerosis. In the nascent state, HDLis secreted in the form of discoidal particles. These particles consistof a bilayer of phospholipids onto which the apolipoproteins (ApoA-I,ApoII and E) are embedded. HDL captures cholesterol esters by the actionof an enzyme, lecithin-cholesterol acyltransferase. HDL is secreted fromthe liver, the small intestine and possibly other tissues.

The ApoA-I CDNA is 878 bp and encodes 267 amino acids, including the 24amino acid propeptide. Increasing the circulating levels of HDL caninfluence or reverse cholesterol transport, and thus reduce thepropensity for forming atherosclerotic plaques. The insertion of thehuman ApoA-I coding sequences into the expression vector serves as anexpression vector for enhanced ApoA-I expression following injection ofplasmid DNA into skeletal muscle. The expression vector ApoA-I hybridgene is effective for long term expression, biosynthesis and secretionof HDL in an ectopic site, and thus increases the content of totalsecretable HDL in blood plasma.

Administration of the vectors can be intravenously, through directinjection or by any one of the methods described above. Dosages willdepend on the severity of the disease and the amount of dosage isreadily determinable by standard methods. The duration of treatment willextend through the course of the disease symptoms which can becontinuously. Alternatively, treatment of atherosclerotic cardiovasculardisease can also be treated by inserting the very low densitylipoprotein (VLDL) receptor gene into the above-described vectors. VLDLhas been described in Chan, Ser. No. 08/149,103 entitled "Human andMouse Very Low Density Lipoprotein Receptors and Methods for Use of SuchReceptors," filed Nov. 8, 1993 hereby incorporated by reference(including drawings).

Treatment of Diabetes

Insulin plays a central role in the regulation of carbohydrate, fat andprotein metabolism. With diabetics, treatment with insulin can result ininsulin resistance in which insulin treatment will not result inadequate metabolic control. This resistance can occur in the presence ofcirculating insulin or insulin-receptor antibodies or insulin-receptorabnormalities or episodically in patients with previously typicalinsulin-dependent diabetes mellitus. Therapeutic options are limitedwith patients suffering from severe insulin resistance.

IGF-I can be used in the treatment of insulin resistance. Treatment withIGF-I using the vectors of the present invention will achieve glycemiccontrol by reversing hyperglycemia and ketoacidosis. Treatment withIGF-I will also improve the degree of insulin sensitivity. Theconvenient cloning sites in the expression vectors of the presentinvention are used to construct vectors containing the IGF-I CDNAsequence. Expression of IGF-I provides insulin like metabolic effects.IGF-I shares sequence homology and biological properties with insulin.

Administration of the vectors can be intravenously, through directinjection or by any one of the methods described above. Dosages willdepend on the severity of the disease and the amount of dosage isreadily determinable by standard methods. The duration of treatment willextend through the course of the disease symptoms which can becontinuously.

Treatment of Peripheral Neuropathies

Peripheral neuropathies are degenerative processes of sensory and motornerves that often result from diabetes, Type I diabetes, Type IIdiabetes, genetic disease such as CHACOTmarie-tooth disease, AIDS,inflammation and side-effects from anti-cancer and anti-viral drugs.Current treatment is limited to pain management, with no treatmentdirected at the underlying cellular causes. Use of recombinant IGF-I hasbeen suggested to restore some of the degenerative processes inperipheral neuropathies and to alleviate some of the associateddysfunction.

Administration of a vector encoding IGF-I to localized muscles afflictedwith peripheral neuropathy by direct injection or hypospray will aid inthe regeneration of neurons, decrease pain sensations, and increasemobility of the affected site. The distinct advantage of vectoradministration of IGF-I is increased levels at needed sites with reducednumbers of administrations. In the diabetic patient dosage schedules mayallow for the combined effect of alleviation of symptoms of peripheralneuropathy and increased efficiency of insulin.

Administration of the vectors can be intravenously, through directinjection or by any one of the methods described above. Dosages willdepend on the severity of the disease and the amount of dosage isreadily determinable by standard methods. The duration of treatment willextend through the course of the disease symptoms which can becontinuously.

Treatment of Osteoporosis

Osteoporosis is a common accelerated loss of bone mass that oftenaccompanies aging. The decreased bone density associated withosteoporosis leads to an increased susceptibility to bone fractures.Treatment with IGF-I is associated with increased bone density.Administration of a vector encoding IGF-I to muscles by direct injectionor hypospray will aid in the redeposition of bone and thereby decreasethe risk of fractures.

Administration of the vectors can be intravenously, through directinjection or by any one of the methods described above. Dosages willdepend on the severity of the disease and the amount of dosage isreadily determinable by standard methods. The duration of treatment willextend through the course of the disease symptoms which can becontinuously.

Treatment of Hemophilia

As described above vector constructs containing human Factor IX havebeen produced that effectively secrete Factor IX into the culture mediaof transfected tissue culture cells. Factor IX levels achievable inthese tissue culture supernatant suggest that adequate Factor IX can beproduced in muscle cells in vivo to achieve a therapeutic level ofauthentic Factor IX in individuals suffering from hemophilia B. FactorIX containing MVS constructs can be administered to hemophiliacs byeither direct muscle injection or hypospray. Sufficient Factor IX canthen be synthesized in vivo to restore clotting times to within normalranges. By constructing a MVS vector that contains the factor VIII geneor an active portion of the gene treatment for hemophilia A can beachieved by a similar method.

Administration of the vectors can be intravenously, through directinjection or by any one of the methods described above. Dosages willdepend on the severity of the disease and the amount of dosage isreadily determinable by standard methods. The duration of treatment willextend through the course of the disease symptoms which can becontinuously.

Treatment of Anemia

An additional embodiment of the present invention is a method for thetreatment of anemia. The vectors of the present invention are wellsuited to express hematologic factors such as erythropoietin (EPO).Following direct injection or hypospray administration of a vectorencoding EPO, muscle cells begin to secrete EPO into the circulationwhere it can increase the production of red blood cells. This therapy isparticularity suited for the treatment of anemia associated with chronicsystemic disease such as inflammation, renal disease, endocrine failureand liver failure. The EPO vector construct has particular advantagesover the convention administration of recombinant EPO in that thefrequency of administration for will be reduced from the current threetimes per day to approximately once per month, depending on the severityof anemia. The doing frequency can easily be adjusted so as to maintainthe patients hematocrit between 0.33 and 0.38.

Administration of the vectors can be intravenously, through directinjection or by any one of the methods described above. Dosages willdepend on the severity of the disease and the amount of dosage isreadily determinable by standard methods. The duration of treatment willextend through the course of the disease symptoms which can becontinuously.

Immune Responses

An additional embodiment of the present invention is a method forproducing an immunological response. The expression vector systems ofthe present invention are well suited for directing the expression of anexogenous protein epitope in muscle and other tissues, and thus, forgenerating vaccines in humans and animals. Targeted sequences areinserted into the cassette of a vector for expression of proteinepitopes for mediating protective immunization. For example, theconstant regions of proteins of HIV subtypes, GP 120, GP 160 and/or GP41 and for cell mediated immunity GP 24, reverse transcriptase,Cytomegalovirus, Respiratory Syncytial Virus, Influenza Virus, HepatitisVirus (A,B,C,D), as well pneumococcus, meningococcus, streptococcus,staphylococcus, heat stable enterotoxins, heat labile enterotoxins,pneumocystitis, the pathogen of lyme disease, aspergillus, candida, andmalaria. One skilled in the art will readily recognize that any othervariety of proteins can be used to generate immunologic response andthus produce antibodies for vaccination. The expression vector is theninjected into the human or animal allowing an immune response to occur.Significantly, the in vivo expression of these antigens in conjunctionwith class I and other immunoregulatory proteins can lead to improvedimmunity characterized by long term persistence with memory T-cells andcellular immune responses in addition to an antibody response.

Administration of the vectors can be intravenously, through directinjection or by any one of the methods described above. Dosages willdepend on the severity of the disease and the amount of dosage isreadily determinable by standard methods. The duration of treatment willextend through the course of the disease symptoms which can becontinuously.

Transgenic Swine

An additional embodiment of the present invention is the 5 generation ofimproved domestic livestock. Specifically, introduction of the vectorSK733IGF-I-3'SK2, or a vector expressing IGF-I of porcine, bovine orovine derivation into oocytes of domestic swine by the method describedabove for the generation of transgenic mice will generate swineexpressing IGF-I in myogenic tissue. These transgenic swine have thedesired livestock characteristics of increased muscle mass and reducedfat.

In addition, by providing contiguous 3' NCR, IGF-I is buffered againstoutside genomic sequences and is thus more protected from positioneffects, when integrated into the genome. In addition, by providingnatural terminating sequences, the additional regulatory sequences thatmark the transcriptional domain of skeletal α-actin prevent read throughtranscription, improve tissue specificity, developmental timing andtranscriptional activity. Presence of 3'NCR sequence allows for a singlecopy of the integrated vector to produce 40-50% of the transcriptionalactivity of the endogenous sequences.

Improvement of Livestock

An additional embodiment of the present invention is the improvement oflivestock by injection of species-specific MSVIGF-I constructs. Muscleinjection of vectors encoding IGF-I by hypodermic or hyposprayadministration will promote increased muscle mass and reduced body fatin important livestock species such as cattle, sheep, swine, rabbits,deer, fish and birds such as turkeys, chickens, ducks, and geese.Administration of the vectors can also be through any one of the methodsdescribed above.

One skilled in the art will readily appreciate that the presentinvention is well adapted to carry out the objects and obtain the endsand advantages mentioned as well as those inherent therein. The vectorsystems along with the methods, procedures treatments and vaccinationsdescribed herein are presently representative of preferred embodimentsare exemplary and not intended as limitations on the scope of theinvention. Changes therein and other uses will occur to those skilled inthe art which are encompassed within the spirit of the invention ordefined by this scope with the claims.

It will be readily apparent to one skilled in the art that varyingsubstitutions and modifications may be made to the invention disclosedherein within departing from the scope and spirit of the invention.

All patents and publications mentioned in the specification areindicative of the levels of those skilled in the art to which theinvention pertains. All patents and publications are herein incorporatedby reference to the same extent as if each individual publication wasspecifically and individually indicated to be incorporated by reference.

    __________________________________________________________________________    SEQUENCE LISTING                                                              (1) GENERAL INFORMATION:                                                      (iii) NUMBER OF SEQUENCES: 10                                                 (2) INFORMATION FOR SEQ ID NO: 1:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 274 base pairs                                                    (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 1:                                      TAAACATGTTTACATGATCACTTTGCCAACCACACTCAGGATGACAATCTTGTAGGTTCC60                AGGCTGCTGAGGACCTGCACCAGCCATGCAACTTTCTATTTTGTAACAATTTCTGGTTAC120               TGTTGCTGCAAAGCCCATGTGACACAGTGTATGTAAAGTGTACATAAATTAATTTATTTT180               ACCTCGTTTTGTTTGTTTTTAAAACCAATGCCCTGTGGAAGGAAACATAAAACTTCAAGA240               AGCATTAAATCATCAGTCATTCTGTCACACCCCT274                                         (2) INFORMATION FOR SEQ ID NO: 2:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 27 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 2:                                      GGTGACTCACCGGGTGAACGGGGCATT27                                                 (2) INFORMATION FOR SEQ ID NO: 3:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 14 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 3:                                      GAGGACGTCCCCAG14                                                              (2) INFORMATION FOR SEQ ID NO: 4:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 18 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 4:                                      GTCATTTAGGGACAACAG18                                                          (2) INFORMATION FOR SEQ ID NO: 5:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 10 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ix) FEATURE:                                                                 (D) OTHER INFORMATION: "N"stands for A or T.                                  (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 5:                                      CCNNNNNNGG10                                                                  (2) INFORMATION FOR SEQ ID NO: 6:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 1610 base pairs                                                   (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 6:                                      TCGAGGATCCGACCTTACCACTTTCACAATCTGCTAGCAAAGGTTATGCAGCGCGTGAAC60                ATGATCATGGCAGAATCACCAGGCCTCATCACCATCTGCCTTTTAGGATATCTACTCAGT120               GCTGAATGTACAGTTTTTCTTGATCATGAAAACGCCAACAAAATTCTGAATCGGCCAAAG180               AGGTATAATTCAGGTAAATTGGAAGAGTTTGTTCAAGGGAACCTTGAGAGAGAATGTATG240               GAAGAAAAGTGTAGTTTTGAAGAAGCACGAGAAGTTTTTGAAAACACTGAAAGAACAACT300               GAATTTTGGAAGCAGTATGTTGATGGAGATCAGTGTGAGTCCAATCCATGTTTAAATGGC360               GGCAGTTGCAAGGATGACATTAATTCCTATGAATGTTGGTGTCCCTTTGGATTTGAAGGA420               AAGAACTGTGAATTAGATGTAACATGTAACATTAAGAATGGCAGATGCGAGCAGTTTTGT480               AAAAATAGTGCTGATAACAAGGTGGTTTGCTCCTGTACTGAGGGATATCGACTTGCAGAA540               AACCAGAAGTCCTGTGAACCAGCAGTGCCATTTCCATGTGGAAGAGTTTCTGTTTCACAA600               ACTTCTAAGCTCACCCGTGCTGAGACTGTTTTTCCTGATGTGGACTATGTAAATTCTACT660               GAAGCTGAAACCATTTTGGATAACATCACTCAAAGCACCCAATCATTTAATGACTTCACT720               CGGGTTGTTGGTGGAGAAGATGCCAAACCAGGTCAATTCCCTTGGCAGGTTGTTTTGAAT780               GGTAAAGTTGATGCATTCTGTGGAGGCTCTATCGTTAATGAAAAATGGATTGTAACTGCT840               GCCCACTGTGTTGAAACTGGTGTTAAAATTACAGTTGTCGCAGGTGAACATAATATTGAG900               GAGACAGAACATACAGAGCAAAAGCGAAATGTGATTCGAATTATTCCTCACCACAACTAC960               AATGCAGCTATTAATAAGTACAACCATGACATTGCCCTTCTGGAACTGGACGAACCCTTA1020              GTGCTAAACAGCTACGTTACACCTATTTGCATTGCTGACAAGGAATACACGAACATCTTC1080              CTCAAATTTGGATCTGGCTATGTAAGTGGCTGGGGAAGAGTCTTCCACAAAGGGAGATCA1140              GCTTTAGTTCTTCAGTACCTTAGAGTTCCACTTGTTGACCGAGCCACATGTCTTCGATCT1200              ACAAAGTTCACCATCTATAACAACATGTTCTGTGCTGGCTTCCATGAAGGAGGTAGAGAT1260              TCATGTCAAGGAGATAGTGGGGGACCCCATGTTACTGAAGTGGAAGGGACCAGTTTCTTA1320              ACTGGAATTATTAGCTGGGGTGAAGAGTGTGCAATGAAAGGCAAATATGGAATATATACC1380              AAGGTATCCCGGTATGTCAACTGGATTAAGGAAAAAACAAAGCTCACTTAATGAAAGATG1440              GATTTCCAAGGTTAATTCATTGGAATTGAAAATTAACAGGGCCTCTCACTAACTAATCAC1500              TTTCCCATCTTTTGTTAGATTTGAATATATACATTCTATGATCATTGCTTTTTCTCTTTA1560              CAGGGGAGAATTTCATATTTTACCTGAGCTGAAGCTTGATATCGAATTCC1610                        (2) INFORMATION FOR SEQ ID NO: 7:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 42 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 7:                                      AACTTGCATGATCTTGTCAAACAACTTCATCTGTACTGCTTG42                                  (2) INFORMATION FOR SEQ ID NO: 8:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 42 base pairs                                                     (B) TYPE: nucleic acid                                                        (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 8:                                      AATTGCATGATCTTGTCAAACAACTTCATCTGTACTGCTTGA42                                  (2) INFORMATION FOR SEQ ID NO: 9:                                             (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 14 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: Peptide                                                   (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 9:                                      AsnLeuHisAspLeuValLysGlnLeuHisLeuTyrCysLeu                                    1510                                                                          (2) INFORMATION FOR SEQ ID NO: 10:                                            (i) SEQUENCE CHARACTERISTICS:                                                 (A) LENGTH: 13 amino acids                                                    (B) TYPE: amino acid                                                          (C) STRANDEDNESS: single                                                      (D) TOPOLOGY: linear                                                          (ii) MOLECULE TYPE: Peptide                                                   (xi) SEQUENCE DESCRIPTION: SEQ ID NO: 10:                                     AsnCysMetIleLeuSerAsnAsnPheIleCysThrAla                                       1510                                                                          __________________________________________________________________________

We claim:
 1. A vector for expression of a nucleic acid sequence intissue, comprising:a 5' flanking region including necessary sequencesfor expression of a nucleic acid cassette; a linker connecting said 5'flanking region to a nucleic acid, said linker having a position forinserting said nucleic acid cassette, wherein said linker lacks thecoding sequence of a gene with which it is naturally associated; and a3' flanking region including a eukaryotic 3'UTR and/or a eukaroyotic3'NCR which stabilizes MRNA expressed from said nucleic acid cassette,wherein said 3' flanking region is 3' to said position for insertingsaid nucleic acid cassette.
 2. The vector of claim 1, wherein saidvector further comprises a nucleic acid cassette.
 3. The vector ofclaims 1 or 2, wherein said 5' flanking region and/or said 3' flankingregion regulates expression of said nucleic acid cassette predominatelyin a specific tissue.
 4. The vector of claim 3, wherein said specifictissue is myogenic.
 5. The vector of claims 1 or 2, wherein said 3' UTRcorresponds to nucleotide 2060 to nucleotide 2331 of the chickenskeletal α-actin gene.
 6. The vector of claims 1 or 2, wherein said 3'UTR and said 3' NCR extend approximately 2.3 Kb from nucleotide 2060 ofthe chicken skeletal α-actin gene.
 7. The vector of claims 1 or 2,wherein said 3' UTR and/or said 3' NCR are derived from a gene selectedfrom the group consisting of skeletal α-actin gene, fast myosin lightchain 1 gene, myosin light chain 1/3 gene, myosin heavy chain gene,tropinin T gene and muscle creatinine kinase gene.
 8. The vector ofclaims 1 or 2 wherein said 5' flanking region includes a promoter, aTATA box, a Cap site and a first intron and intron/exon boundary inappropriate relationship for expression of said nucleic acid cassette.9. The vector of claim 8, wherein said 5' flanking region furthercomprises a 5' mRNA leader sequence inserted between said promoter andsaid nucleic acid cassette.
 10. The vector of claims 1 or 2, furthercomprising a coating to enhance cellular uptake.
 11. The vector of claim10, wherein said coating comprises:a DNA initiation complex; andhistones.
 12. The vector of claim 11, wherein said DNA initiationcomplex comprises:a serum response factor; a serum response element,wherein said serum response factor interacts with said serum responseelement within a promoter region of said vector; 5 a transcriptioninitiation factor; and a transregulatory factor; wherein saidtranscription initiation factor and said transregulatory factor interactwith said serum response factor and said promoter to form a stablecomplex.
 13. The vector of claims 1 or 2, further comprising aregulatory system for regulating the expression of said nucleic acidcassette.
 14. The vector of claim 13, wherein said regulatory systemcomprises:a chimeric trans-acting regulatory factor located within apromoter sequence of said vector, wherein said chimeric trans-actingregulatory factor incorporates a serum response factor with a DNAbinding domain sequence of a receptor; an agent capable of binding tosaid DNA binding domain sequence of said receptor; and a transactivationdomain within said serum response factor, wherein said transactivationdomain regulates transcription when said agent binds said DNA bindingdomain sequence of said receptor.
 15. The vector of claim 14 whereinsaid DNA binding domain sequence of said receptor is selected from thegroup consisting of vitamin, steroid, thyroid, orphan, hormone, retinoicacid, thyroxine or GAL4 receptors.
 16. The vector of claim 14 whereinsaid promoter sequence is an a-actin promoter sequence, said DNA bindingdomain sequence of said receptor is from a Vitamin D receptor and saidagent is Vitamin D.
 17. A vector containing a regulatory system for 5expression of a nucleic acid sequence in tissue, comprising:a firstfunctional unit comprising a promoter, a nucleic acid sequence codingfor a receptor and a 3' UTR and/or a 3'NCR; an agent which binds to saidreceptor; and a second functional unit, comprising a response elementcorresponding to said receptor, a promoter, a nucleic acid cassette, anda eukaryotic 3'UTR and/or a eukaryotic 3'NCR; wherein said 3'UTR and/orsaid 3'NCR provides said MRNA stability; wherein said first functionalunit expresses said receptor, said receptor forms an interaction betweensaid response element and said agent which binds to said receptor, saidinteraction regulates the expression of said nucleic acid cassette. 18.The vector of claim 17 wherein said first functional unit and saidsecond functional unit are in the same vector.
 19. The vector of claim17, wherein said first functional unit and said second functional unitare in separate vectors.
 20. The vector of claim 17, wherein saidreceptor is selected from the group consisting of vitamin, steroid,thyroid, orphan, hormone, retinoic acid, thyroxine or GAL4 receptors.21. The vector of claim 17, wherein said receptor is a Vitamin Dreceptor, said response element is a Vitamin D response element and saidagent is Vitamin D.
 22. A cell transformed with a vector for expressionof a nucleic acid sequence in tissue, comprising:a nucleic acidcassette; a 5' flanking region including necessary sequences forexpression of a nucleic acid cassette; a linker connecting said 5'flanking region to a nucleic acid, said linker having a position forinserting said nucleic acid cassette, wherein said linker lacks thecoding sequence of a gene with which it is naturally associated; and a3' flanking region including a eukaroytic 3' UTR and/or a eukaroytic 3'NCR which stabilizes MRNA expressed from said nucleic acid cassette,wherein said 3' flanking region is 3' to said position for insertingsaid nucleic acid cassette.
 23. The transformed cell of claim 22,wherein said cell is myogenic.
 24. A method for transfection of a cellin situ comprising the step of contacting said cell with a vector forsufficient time to transfect said cell, wherein said vector comprises:anucleic acid cassette; a 5' flanking region including necessarysequences for expression of a nucleic acid cassette; a linker connectingsaid 5' flanking region to a nucleic acid, said linker having a positionfor inserting said nucleic acid cassette, wherein said linker lacks thecoding sequence of a gene with which it is naturally associated; and a3' flanking region including a eukaroytic 3' UTR and/or a eukaryotic 3'NCR which stabilizes MRNA expressed from said nucleic acid cassette,wherein said 3' flanking region is 3' to said position for insertingsaid nucleic acid cassette.
 25. The method of claim 24, whereintransfection of said cell is in vivo.
 26. The method of claim 24,wherein transfection of said cell is ex vivo, further comprising thesteps of cotransfecting said vector with a selectable marker andselecting the transformed cells.